tikz-vowel.sty

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% tikz-vowel.sty
%% Copyright 2016-2017 by Christopher Weedall <chris.weedall@anu.edu.au>
%
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.3
% of this license or (at your option) any later version.
% The latest version of this license is in
%   http://www.latex-project.org/lppl.txt
% and version 1.3 or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
%
% This work has the LPPL maintenance status `author-maintained'.
% 
% The Current Maintainer of this work is Christopher Weedall.
%
% This work consists of the files tikz-vowel.dtx, tikz-vowel.ins, tikz-vowel.tex, tikz-vowel.pdf
% and the derived file tikz-vowel.sty.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% based on TikZ implementation of vowel chart from:
% 	http://tex.stackexchange.com/questions/156955/tikz-pgf-linguistics-vowel-chart
% based on concepts in vowel.sty Copyright 2002 by Rei Fukui
% based on concepts in pst-vowel.sty Copyright 2009 by Alan Munn
%
% This package creates a sagittal grid based on the IPA vowel grid.
%
% The grid is created within a tikz-picture environment.
%
% Coordinates for cardinal vowels are created which correspond to the 16 vowel nodes
% which exist in vowel.sty.  There are two coordinates for each vowel.
% The first coordinate is labeled with an ordinal numeral (e.g. 1, 2, 3, etc.) while 
% the second coordinate is labeled with `v' prepended to the ordinal numeral (e.g. v1, v2, v3, etc.)
%
% Several new commands are created which mirror the concept of vowel.sty,
% but have additional options available.  For example, instead of being limited to 
% `left' and `right' for the label of a vowel, `above', `below' and the corners
% `above left', `above right', etc. are allowed.  Another example is the introduction
% of a `scale' optional argument.
%
% Similar to the pst-vowel.sty package, there are four methods that allow
% diphthong lines and labels to be created.  One for diphthongs between cardinal vowels,
% another from a cardinal vowel to a manual coordinate, another from a manual 
% coordinate to a cardinal vowel, and the last between two manual coordinates.
%
% No code was taken directly from either vowel.sty or pst-vowel.sty.
% However, the commands provided inspiration for this package to 
% accomplish the same/similar with little-to-no learning curve.
%
% This package uses coordinate, node, and draw commands from the
% tikz package .  TikZ is used to essentially draw everything.
%
% Version 1.0 2017/03/18
% Version 1.1 2019/08/18
% Version 1.2 2020/12/13
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%\RequirePackage{expl3}
\ProvidesExplPackage
	% Package name
	{tikz-vowel}
	% Release date
	{2020/12/13}
	% Release version          
	{1.2}
	% Description
	{tikz-vowel package provides an environment allowing a (stylized) sagittal view for vowel plotting.}
%
%DEPRECATED,REPLACED WITH LINE BELOW%\RequirePackage{l3regex}%
\RequirePackage{expl3}
\RequirePackage{xstring}%
\RequirePackage{xparse}%
\RequirePackage{environ}%
%
\RequirePackage{tikz}%
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%%%%FIX - PATCH TIKZ TO FOLLOW LATEX2E WITHIN THE LATEX3 ENVIRONMENT
\RequirePackage{etoolbox}
\ExplSyntaxOff
\patchcmd
	{\pgfutil@InputIfFileExists}
	{\input #1}
	{%
	\@pushfilename
	\expandafter\expandafter\expandafter\input #1 %
	\@popfilename
	}
	{}{}
\usetikzlibrary{arrows.meta,backgrounds,calc,fit,intersections,positioning,shapes.misc,shapes.geometric}%
%\usetikzlibrary{external}%
%\tikzexternalize%
%\tikzset{external/force remake}
%
\ExplSyntaxOn
%
%%% Set default label styles
\tikzset
{%
	tikzvowel~labels/.style=		{font=\footnotesize,},
	tikzvowel~top~labels/.style=	{},
	tikzvowel~side~labels/.style=	{anchor=east,align=right,},
}%
%
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%
% Generate a nfT variant for \regex_match:nnT
\cs_generate_variant:Nn \regex_match:nnT {nfT}
%
% Generate a nVTF variant for \regex_match:nnTF
\cs_generate_variant:Nn \regex_match:nnTF {nVTF}
%
% Generate a xVTF variant for \regex_match:nVTF
\cs_generate_variant:Nn \regex_match:nVTF {xVTF}
%
% Generate a xnNF variant for \regex_replace_once:nnNF
\cs_generate_variant:Nn \regex_replace_once:nnNF {xnNF}
%
% Generate a NT variant for \tl_if_blank:nT
%\cs_generate_variant:Nn \tl_if_blank:nT {NT}% <---- 'N' is DEPRECATED
\cs_generate_variant:Nn \tl_if_blank:nT {VT}
%
%----------------------------------------------------------------------
%	Define the x and y coordinates of vowel nodes v1 - v16
%		-see `Create vowel coordinates (node) v1 - v16 using x and y coordinates' for creation of TikZ coordinates/nodes
%----------------------------------------------------------------------
%Vowel i	-	Node v1 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV1_tl } 
\tl_gset:cn { g_tikzvowel_xV1_tl } { 0 }
\tl_new:c { g_tikzvowel_yV1_tl }
\tl_gset:cn { g_tikzvowel_yV1_tl } { 3 }
%Vowel e	-	Node v2 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV2_tl }
\tl_gset:cn { g_tikzvowel_xV2_tl } { 0.66666 }
\tl_new:c { g_tikzvowel_yV2_tl }
\tl_gset:cn { g_tikzvowel_yV2_tl } { 2 }
%Vowel ɛ	-	Node v3 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV3_tl }
\tl_gset:cn { g_tikzvowel_xV3_tl } { 1.33333 }
\tl_new:c { g_tikzvowel_yV3_tl }
\tl_gset:cn { g_tikzvowel_yV3_tl } { 1 }
%Vowel a	-	Node v4 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV4_tl }
\tl_gset:cn { g_tikzvowel_xV4_tl } { 2 }
\tl_new:c { g_tikzvowel_yV4_tl }
\tl_gset:cn { g_tikzvowel_yV4_tl } { 0 }
%Vowel ɑ	-	Node v5 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV5_tl }
\tl_gset:cn { g_tikzvowel_xV5_tl } { 4 }
\tl_new:c { g_tikzvowel_yV5_tl }
\tl_gset:cn { g_tikzvowel_yV5_tl } { 0 }
%Vowel ɔ	-	Node v6 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV6_tl }
\tl_gset:cn { g_tikzvowel_xV6_tl } { 4 }
\tl_new:c { g_tikzvowel_yV6_tl }
\tl_gset:cn { g_tikzvowel_yV6_tl } { 1 }
%Vowel o	-	Node v7 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV7_tl }
\tl_gset:cn { g_tikzvowel_xV7_tl } { 4 }
\tl_new:c { g_tikzvowel_yV7_tl }
\tl_gset:cn { g_tikzvowel_yV7_tl } { 2 }
%Vowel u	-	Node v8 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV8_tl }
\tl_gset:cn { g_tikzvowel_xV8_tl } { 4 }
\tl_new:c { g_tikzvowel_yV8_tl }
\tl_gset:cn { g_tikzvowel_yV8_tl } { 3 }
%Vowel ɨ	-	Node v9 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV9_tl }
\tl_gset:cn { g_tikzvowel_xV9_tl } { 2 }
\tl_new:c { g_tikzvowel_yV9_tl }
\tl_gset:cn { g_tikzvowel_yV9_tl } { 3 }
%Vowel ɘ	-	Node v10 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV10_tl }
\tl_gset:cn { g_tikzvowel_xV10_tl } { 2.33333 }
\tl_new:c { g_tikzvowel_yV10_tl }
\tl_gset:cn { g_tikzvowel_yV10_tl } { 2 }
%Vowel ə	-	Node v11 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV11_tl }
\tl_gset:cn { g_tikzvowel_xV11_tl } { 2.5 }
\tl_new:c { g_tikzvowel_yV11_tl }
\tl_gset:cn { g_tikzvowel_yV11_tl } { 1.5 }
%Vowel ɜ	-	Node v12 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV12_tl }
\tl_gset:cn { g_tikzvowel_xV12_tl } { 2.66666 }
\tl_new:c { g_tikzvowel_yV12_tl }
\tl_gset:cn { g_tikzvowel_yV12_tl } { 1 }
%Vowel ɪ	-	Node v13 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV13_tl }
\tl_gset:cn { g_tikzvowel_xV13_tl } { 1.2 }
\tl_new:c { g_tikzvowel_yV13_tl }
\tl_gset:cn { g_tikzvowel_yV13_tl } { 2.5 }
%Vowel ʊ	-	Node v14 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV14_tl }
\tl_gset:cn { g_tikzvowel_xV14_tl } { 3.3 }
\tl_new:c { g_tikzvowel_yV14_tl }
\tl_gset:cn { g_tikzvowel_yV14_tl } { 2.5 }
%Vowel ɐ	-	Node v15 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV15_tl }
\tl_gset:cn { g_tikzvowel_xV15_tl } { 2.8 }
\tl_new:c { g_tikzvowel_yV15_tl }
\tl_gset:cn { g_tikzvowel_yV15_tl } { 0.6 }
%Vowel æ	-	Node v16 (x + y coordinates)
\tl_new:c { g_tikzvowel_xV16_tl }
\tl_gset:cn { g_tikzvowel_xV16_tl } { 1.66666 }
\tl_new:c { g_tikzvowel_yV16_tl }
\tl_gset:cn { g_tikzvowel_yV16_tl } { 0.5 }
%
%
% Create a temporary token list to store and modify the value of a regex match (plus changes)
\tl_if_exist:NF \l_tikzvowel_update_tl
	{ \tl_new:N \l_tikzvowel_update_tl }
\tl_set:Nn \l_tikzvowel_update_tl { }
%
% Create a temporary token list to store and modify the value of a regex match (plus changes)
\tl_if_exist:NF \l_tikzvowel_temp_tl
	{ \tl_new:N \l_tikzvowel_temp_tl }
\tl_set:Nn \l_tikzvowel_temp_tl { }
%
% Create a temporary token list to store X,Y coordinates and remove commas
\tl_if_exist:NF \l_tikzvowel_temp_XY_remove_comma_tl
	{ \tl_new:N \l_tikzvowel_temp_XY_remove_comma_tl }
\tl_set:Nn \l_tikzvowel_temp_XY_remove_comma_tl { }
%
% Create a new token list to store the node commands
\tl_if_exist:NF \g_tikzvowel_nodes_tl
	{ \tl_new:N \g_tikzvowel_nodes_tl }
\tl_gset:Nx \g_tikzvowel_nodes_tl { }
%
% Create a new token list to store the draw commands
\tl_if_exist:NF \g_tikzvowel_draw_tl
	{ \tl_new:N \g_tikzvowel_draw_tl }
\tl_gset:Nx \g_tikzvowel_draw_tl { }
%
% Create a new token list to store the fixed vowel node label/name
\tl_if_exist:NF \l_tikzvowel_stripped_label_tl
	{ \tl_new:N \l_tikzvowel_stripped_label_tl }
\tl_set:Nx \l_tikzvowel_stripped_label_tl { }
%
%Create a counter, set to 0, for creating coordinates
\int_if_exist:NF \l_tikzvowel_counter_int
	{ \int_new:N \l_tikzvowel_counter_int }
\int_zero:N \l_tikzvowel_counter_int
%
% Create a new int variable to store the cardinal vowel number
\int_if_exist:NF \l_tikzvowel_cardinal_vowel_number_int
	{ \int_new:N \l_tikzvowel_cardinal_vowel_number_int }
% Set default cardinal vowel number to 0 (this is invalid, and should be changed within a function)
\int_zero:N \l_tikzvowel_cardinal_vowel_number_int
%
% Create a sequence (i.e. list of tokens) to aid in separating X and Y
\seq_if_exist:NF \l_tikzvowel_coordinates_seq
	{ \seq_new:N \l_tikzvowel_coordinates_seq }
%
% Create a sequence (i.e. list of tokens) to aid in separating starting X and Y
\seq_if_exist:NF \l_tikzvowel_starting_coordinates_seq
	{ \seq_new:N \l_tikzvowel_starting_coordinates_seq }
% Create a sequence (i.e. list of tokens) to aid in separating ending X and Y
\seq_if_exist:NF \l_tikzvowel_ending_coordinates_seq
	{ \seq_new:N \l_tikzvowel_ending_coordinates_seq }
%
%
%----------------------------------------------------------------------
%	Create vowel coordinates (node) v1 - v16 using x and y coordinates
%		-see `Define the x and y coordinates of vowel nodes v1 - v16' for details
%----------------------------------------------------------------------
%\DeclareDocumentCommand{\cs_tikzvowel_populate_cardinal_vowel_coordinates}{}
\cs_new:Nn \cs_tikzvowel_populate_cardinal_vowel_coordinates:
{%
	% Re/set counter to 0, for creating coordinates
	\int_zero:N \l_tikzvowel_counter_int
	
	%Create coordinates (nodes) with a label such as v1, v2, ... v16 and 1, 2, ... 16
	\int_while_do:nn { \l_tikzvowel_counter_int < 16 }
	{%
		%Increment counter by 1 first
		\int_incr:N \l_tikzvowel_counter_int

		%Create vNUM coordinate
		\coordinate (v\int_use:N \l_tikzvowel_counter_int ) 
		at ( \tl_use:c { g_tikzvowel_xV\int_use:N \l_tikzvowel_counter_int _tl } , 
			\tl_use:c { g_tikzvowel_yV\int_use:N \l_tikzvowel_counter_int _tl });%
		%Create NUM coordinate
		\coordinate ( \int_use:N \l_tikzvowel_counter_int ) 
		at ( \tl_use:c { g_tikzvowel_xV\int_use:N \l_tikzvowel_counter_int _tl } , 
			\tl_use:c { g_tikzvowel_yV\int_use:N \l_tikzvowel_counter_int _tl });%
	}%
}%
%
%----------------------------------------------------------------------
%	Create top labels (`Front', `Central', `Back')
%----------------------------------------------------------------------
\cs_new:Nn \cs_tikzvowel_draw_top_labels:
{%
	%Top labels
	\node[tikzvowel~labels,tikzvowel~top~labels] (FrontLabel) at (0, 3.65) {Front};
	\node[tikzvowel~labels,tikzvowel~top~labels] (CentralLabel) at (2, 3.65) {Central};
	\node[tikzvowel~labels,tikzvowel~top~labels] (BackLabel) at (4, 3.65) {Back};
}%
%
%----------------------------------------------------------------------
%	Create side labels (`Close', `Close-mid', `Open-mid', `Open')
%----------------------------------------------------------------------
\cs_new:Nn \cs_tikzvowel_draw_side_labels:
{%
	%Left side labels
	\node[tikzvowel~labels,tikzvowel~side~labels] (CloseLabel) at (-0.65, 3) {Close};
	\node[tikzvowel~labels,tikzvowel~side~labels] (ClosemidLabel) at (-0.65, 2) {Close-mid};
	\node[tikzvowel~labels,tikzvowel~side~labels] (OpenmidLabel) at (-0.65, 1) {Open-mid};
	\node[tikzvowel~labels,tikzvowel~side~labels] (OpenLabel) at (-0.65, 0) {Open};
}%
%
%----------------------------------------------------------------------
%	Create cardinal vowel node with a label (or name)
%		-argument #1 (optional) is the location of the label (if unspecified, `center' is default)
%			-see TikZ for details and all available values
%			-available values (typical):
%				`center' [default]
%				`left'
%				`right'
%				`above'
%				`below'
%				`above left'
%				`above right'
%				`below left'
%				`below right'
%		-argument #2 (required) is the vowel node label/name
%		-argument #3 (required) is the vowel node location
%			-see `Define the x and y coordinates of vowel nodes v1 - v16' for details
%----------------------------------------------------------------------
\DeclareDocumentCommand{\cardinalvowel}{ O{center} m m }
{%
	% Error checking for #2 (vowel label/name) - is empty?
	\tl_if_empty:nT {#2} 
		{ \PackageError{tikz-vowel:\cardinalvowel}{Label/name~for~vowel~node~is~undefined}{} }
	% Error checking for #3 (vowel node location) - is empty?
	\tl_if_empty:nT {#3}
		{ \PackageError{tikz-vowel:\cardinalvowel}{Vowel~node~location~is~undefined}{} }

	% Error checking for #2 (vowel label/name) - is blank?
	\tl_if_blank:nT {#2} 
		{ \PackageError{tikz-vowel:\cardinalvowel}{Label/name~for~vowel~node~is~undefined}{} }
	% Error checking for #3 (vowel node location) - is blank?
	\tl_if_blank:nT {#3}
		{ \PackageError{tikz-vowel:\cardinalvowel}{Vowel~node~location~is~undefined}{} }
	
	% Error checking for #3 (vowel node location) - contains unwanted letters/numbers/characters?
	\regex_match:nnT { [^v0-9] } { #3 }
	{%
		% Unexpected character(s) found - throw error
		\PackageError{tikz-vowel:\cardinalvowel}
			{Vowel~node~'#3'~is~invalid.~
			Must~be~1-16~OR~v1-v16}
			{}%
	}%

	% Re/set default cardinal vowel number to 0 (this is invalid, but is changed immediately)
	\int_zero:N \l_tikzvowel_cardinal_vowel_number_int
	% Check if #3 (vowel node location) contains 'v'
	\regex_match:nnTF { [v] } { \tl_head:n {#3} } 
	{%
		%If true - strip v to get cardinal vowel number
		\int_set:Nn \l_tikzvowel_cardinal_vowel_number_int { \tl_tail:n {#3} }
	}
	{%
		%If false - there is no v, meaning already cardiinal vowel number
		\int_set:Nn \l_tikzvowel_cardinal_vowel_number_int { #3 }
	}%

	% Error check - is the numerical value of #3 between 1 and 16 (inclusive)?
	% first, check if vowel is less than 1
	\int_compare:nNnTF { \l_tikzvowel_cardinal_vowel_number_int } < { 1 }
	{%
		% Error! - cardinal vowel number is less than 1
		\PackageError{tikz-vowel:\cardinalvowel}
			{Vowel~'#2'~at~node~'#3'~(i.e.~less~than~1).~
			Must~be~1-16~OR~v1-v16}
			{}
	}
	{%
		% If vowel is not less than 1, check if greater than 16
		\int_compare:nNnT { \l_tikzvowel_cardinal_vowel_number_int } > { 16 }
		{%
			% Error! - the vowel node number is greater than 16
			\PackageError{tikz-vowel:\cardinalvowel}
				{Vowel~'#2'~at~node~'#3'~(i.e.~greater~than~16).~
				Must~be~1-16~OR~v1-v16}
				{}%
		}%
	}%

	% Set the token list to the string value (NOT actual macros/commands) of the label/name
	\tl_set:Nx \l_tikzvowel_stripped_label_tl { \tl_to_str:n {#2} }

	% Replace anything matching a command ( \ NAME { ) or a closing curly bracket with nothing
	% (i.e. delete macro/command-related stuff - it's not allowed for the tikz node name
	% ***WARNING***
	% This may not cover all commands... it may need to be updated or added to eventually
	% to account for additional complicated situations
	\regex_replace_all:nnN { [\\]([^\\]*?)[\{]|[\}] } {} \l_tikzvowel_stripped_label_tl
	\regex_replace_all:nnN { [\\]([^\\]*?)\s+ } {} \l_tikzvowel_stripped_label_tl

	% Check if vowel label/name has no location value specified
	\IfNoValueTF {#1}
	{%
		% Vowel label/name has no location value specified
		\tl_gput_right:Nx \g_tikzvowel_nodes_tl
			{%
				\exp_not:N \node ( \exp_not:V \l_tikzvowel_stripped_label_tl ) 
					[vowelLetter]
					at ( \tl_use:c { g_tikzvowel_xV\int_use:N \l_tikzvowel_cardinal_vowel_number_int _tl } , 
						\tl_use:c { g_tikzvowel_yV\int_use:N \l_tikzvowel_cardinal_vowel_number_int _tl } ) 
				{\exp_not:n {#2}};%
			}%
	}
	{%
		% Vowel label/name has location value specified
		% check if location value is 'center'
		\tl_if_eq:nnTF { #1 } { center }
		{%
			% Location value is 'center'
			% so, NO dot
			% AND place label/name at the center
			\tl_gput_right:Nx \g_tikzvowel_nodes_tl
			{%
				\exp_not:N \node ( \exp_not:V \l_tikzvowel_stripped_label_tl )
					[vowelLetter]
					at ( \tl_use:c { g_tikzvowel_xV\int_use:N \l_tikzvowel_cardinal_vowel_number_int _tl } , 
						\tl_use:c { g_tikzvowel_yV\int_use:N \l_tikzvowel_cardinal_vowel_number_int _tl } ) 
					{\exp_not:n {#2}};%\exp_not:n {#2
			}%
		}
		{%
			% Location value is not 'center'
			% so, need a dot at the node
			% AND need to place the label/name at specified location
			\tl_gput_right:Nx \g_tikzvowel_nodes_tl
			{%
				\exp_not:N \node ( \exp_not:V \l_tikzvowel_stripped_label_tl )
					[vowelDot,
					label={[vowelLabel,
							#1=of~\exp_not:V \l_tikzvowel_stripped_label_tl,
							anchor=mid]\exp_not:n {#2}}]
					at ( \tl_use:c { g_tikzvowel_xV\int_use:N \l_tikzvowel_cardinal_vowel_number_int _tl } , 
						\tl_use:c { g_tikzvowel_yV\int_use:N \l_tikzvowel_cardinal_vowel_number_int _tl } ) 
					{};%
			}%
		}%
	}%
}%
%----------------------------------------------------------------------
%	Create (custom) vowel node at X, Y coordinates with a label (or name)
%		-argument #1 (optional) is the location of the label (if unspecified, `center' is default)
%			-see TikZ for details and all available values
%			-available values (typical):
%				`center' [default]
%				`left'
%				`right'
%				`above'
%				`below'
%				`above left'
%				`above right'
%				`below left'
%				`below right'
%		-argument #2 (required) is the vowel node label/name
%		-argument #3 (required) is the vowel node location defined by (X, Y) or X,Y
%			-notation should be `x,y' (spaces are irrelevant)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\xyvowel}{ O{center} m D(){} }
{%
	% Error checking for #3 (vowel node location) - is empty?
	\tl_if_empty:nT {#3}
		{ \PackageError{tikz-vowel:\xyvowel}{Vowel~node~location~is~undefined}{} }

	% Error checking for #3 (vowel node location) - is blank?
	\tl_if_blank:nT {#3}
		{ \PackageError{tikz-vowel:\xyvowel}{Vowel~node~location~is~undefined}{} }
	
	% Error checking for #3 (vowel node location) - 
	% Contains unwanted letters/numbers/characters?
	\regex_match:nnT { [^0-9\-.,()] } { #3 }
	{%
		% Unexpected character(s) found - throw error
		\PackageError{tikz-vowel:\xyvowel}
			{Vowel~node~'#3'~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}%
	}%
		
	% Split the values for X and Y, based on a comma
	\regex_split:nnNF { , } { #3 } \l_tikzvowel_coordinates_seq
		{%
			% No , character was found - throw error.
			\PackageError{tikz-vowel:\xyvowel}
				{Vowel~'#2'~has~invalid~location~'#3'.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}%
		}%
 	
 	% Error check - 
	% Check if less than 1 element in the sequence (this should never happen).
	\int_compare:nNnTF { \seq_count:N \l_tikzvowel_coordinates_seq } < { 1 }
	{%
 		% If less than 1, something serious occurred - throw error.
 		\PackageError{tikz-vowel:\xyvowel}
			{Vowel~'#2'~has~invalid~location~'#3'.~
			Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}%
 	}
 	{%
 		% Error check -
 		% Check if greater than 2 elements in the sequence
 		\int_compare:nNnTF { \seq_count:N \l_tikzvowel_coordinates_seq } > { 2 }
 		{%
 			% If greater than 2, user typed something wrong - throw error.
 			\PackageError{tikz-vowel:\xyvowel}
				{Vowel~'#2'~has~invalid~location~'#3'.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}%
 		}%
 	}%
	
	% Call \anyvowel command.
	\anyvowel 	[#1]
				{#2}
				{\seq_item:Nn \l_tikzvowel_coordinates_seq {1}}
				{\seq_item:Nn \l_tikzvowel_coordinates_seq {2}}%
}%
%----------------------------------------------------------------------
%	Create (custom) vowel node at X, Y coordinates with a label (or name)
%		-argument #1 (optional) is the location of the label (if unspecified, `center' is default)
%			-see TikZ for details and all available values
%			-available values (typical):
%				`center' [default]
%				`left'
%				`right'
%				`above'
%				`below'
%				`above left'
%				`above right'
%				`below left'
%				`below right'
%		-argument #2 (required) is the vowel node label/name
%		-argument #3 (required) is the vowel node X coordinate location
%		-argument #4 (required) is the vowel node Y coordinate location
%----------------------------------------------------------------------
\DeclareDocumentCommand{\anyvowel}{ O{center} m m m }
{%
	% Error checking for #2 (vowel label/name) - is empty?
	\tl_if_empty:nT {#2} 
		{ \PackageError{tikz-vowel:\anyvowel}{Label/name~for~vowel~node~is~undefined}{} }
	% Error checking for #3 (vowel node X coordinate) - is empty?
	\tl_if_empty:nT {#3}
		{ \PackageError{tikz-vowel:\anyvowel}{Vowel~x-axis~value~is~undefined}{} }
	% Error checking for #4 (vowel node Y coordinate) - is empty?
	\tl_if_empty:nT {#4}
		{ \PackageError{tikz-vowel:\anyvowel}{Vowel~y-axis~value~is~undefined}{} }

	% Error checking for #2 (vowel label/name) - is blank?
	\tl_if_blank:nT {#2} 
		{ \PackageError{tikz-vowel:\anyvowel}{Label/name~for~vowel~node~is~undefined}{} }
	% Error checking for #3 (vowel node X coordinate) - is blank?
	\tl_if_blank:nT {#3}
		{ \PackageError{tikz-vowel:\anyvowel}{Vowel~x-axis~value~is~undefined}{} }
	% Error checking for #4 (vowel node X coordinate) - is blank?
	\tl_if_blank:nT {#4}
		{ \PackageError{tikz-vowel:\anyvowel}{Vowel~y-axis~value~is~undefined}{} }
	
	% Error checking for #3 (vowel x-axis value) - contains unwanted letters/numbers/characters?
	\regex_match:nfT {[^0-9\-\.]} { #3 }
	{%
		% Unexpected character(s) found - throw error
		\PackageError{tikz-vowel:\anyvowel}
			{Vowel~x-axis~value~'#3'~is~invalid.~
			Must~be~an~integer~or~decimal}
			{}%
	}%
	
	% Error checking for #4 (vowel y-axis value) - contains unwanted letters/numbers/characters?
	\regex_match:nfT {[^0-9\-\.]} { #4 }
	{%
		% Unexpected character(s) found - throw error
		\PackageError{tikz-vowel:\anyvowel}
			{Vowel~x-axis~value~'#4'~is~invalid.~
			Must~be~an~integer~or~decimal}
			{}%
	}%
	
	% Warning check - 
	% Is the vowel X-axis coordinate is less than 0 (vowel chart is between 0 and 4 width)?
	\fp_compare:nNnTF { #3 } < { 0 }
	{%
		% X-axis coordinate is less than 0 - throw warning
		\PackageWarning{tikz-vowel:\anyvowel}
			{Vowel~'#2'~at~X~value~'#3'~(i.e.~less~than~0).~
			The~X-axis~for~the~vowel~chart~starts~at~0~(left~side)~
			and~goes~to~4~(right~side).~
			You~can~go~outside~this,~but~your~vowel~placement~may~be~unexpected.}
			{}%
	}
	{%
		% Warning check - 
		% Is the vowel X-axis coordinate is greater than 4 (vowel chart is between 0 and 4 width)?
		\fp_compare:nNnT { #3 } > { 4 }
		{%
			% X-axis coordinate is greater than 4 - throw warning
			\PackageWarning{tikz-vowel:\anyvowel}
				{Vowel~'#2'~at~X~value~'#3'~(i.e.~greater~than~4).~
				The~X-axis~for~the~vowel~chart~starts~at~0~(left~side)~
				and~goes~to~4~(right~side).~
				You~can~go~outside~this,~but~your~vowel~placement~may~be~unexpected.}
				{}%
		}%
	}%
	
	% Warning check - 
	% Is the vowel Y-axis coordinate is less than 0 (vowel chart is between 0 and 3 height)?
	\fp_compare:nNnTF { #4 } < { 0 }
	{%
		% Y-axis coordinate is less than 0 - throw warning
		\PackageWarning{tikz-vowel:\anyvowel}
			{Vowel~'#2'~at~Y~value~'#4'~(i.e.~less~than~0).~
			The~Y-axis~for~the~vowel~chart~starts~at~0~(bottom~side)~
			and~goes~to~3~(top~side).~
			You~can~go~outside~this,~but~your~vowel~placement~may~be~unexpected.}
			{}%
	}
	{%
		% Warning check - 
		% Is the vowel X-axis coordinate is greater than 3 (vowel chart is between 0 and 3 height)?
		\fp_compare:nNnT { #4 } > { 3 }
		{%
			% Y-axis coordinate is greater than 3 - throw warning
			\PackageWarning{tikz-vowel:\anyvowel}
				{Vowel~'#2'~at~Y~value~'#4'~(i.e.~greater~than~3).~
				The~Y-axis~for~the~vowel~chart~starts~at~0~(bottom~side)~
				and~goes~to~3~(top~side).~
				You~can~go~outside~this,~but~your~vowel~placement~may~be~unexpected.}
				{}%
		}%
	}%
	
	% Set the token list to the string value (NOT actual macros/commands) of the label/name
	\tl_set:Nx \l_tikzvowel_stripped_label_tl { \tl_to_str:n {#2} }

	% Replace anything matching a command ( \ NAME { ) or a closing curly bracket with nothing
	% (i.e. delete macro/command-related stuff - it's not allowed for the tikz node name
	% ***WARNING***
	% This may not cover all commands... it may need to be updated or added to eventually
	% to account for additional complicated situations
	\regex_replace_all:nnN { [\\]([^\\]*?)[\{]|[\}] } {} \l_tikzvowel_stripped_label_tl
	\regex_replace_all:nnN { [\\]([^\\]*?)\s+ } {} \l_tikzvowel_stripped_label_tl

	% Check if vowel label/name has no location value specified
	\IfNoValueTF {#1}
	{%
		% Vowel label/name has no location value specified
		\tl_gput_right:Nx \g_tikzvowel_nodes_tl
			{%
				\exp_not:N \node ( \exp_not:V \l_tikzvowel_stripped_label_tl ) 
					[vowelLetter]
					at ( #3 , #4 ) 
					{\exp_not:n {#2}};%
			}%
	}
	{%
		% Vowel label/name has location value specified
		% check if location value is 'center'
		\tl_if_eq:nnTF { #1 } { center }
		{%
			% Location value is 'center'
			% so, NO dot
			% AND place label/name at the center
			\tl_gput_right:Nx \g_tikzvowel_nodes_tl
			{%
				\exp_not:N \node ( \exp_not:V \l_tikzvowel_stripped_label_tl ) 
					[vowelLetter]
					at ( #3 , #4 ) 
					{\exp_not:n {#2}};%
			}%
		}
		{%
			% Location value is not 'center'
			% so, need a dot at the node
			% AND need to place the label/name at specified location
			\tl_gput_right:Nx \g_tikzvowel_nodes_tl
				{%
					\exp_not:N \node ( \exp_not:V \l_tikzvowel_stripped_label_tl )
						[vowelDot,
						label={[vowelLabel,
								#1=of~\exp_not:V \l_tikzvowel_stripped_label_tl,
								anchor=mid]\exp_not:n {#2}}]
					at ( #3 , #4 ) 
					{};%
				}%
		}%
	}%
}%
%----------------------------------------------------------------------
%	Diphthong between two cardinal vowels
%		-argument #1 (optional) is the bend of the line (left or right)
%		-argument #2 (required) is the starting point (coordinate/node) for the line
%		-argument #3 (optional) is the degree of bend in the line (0 = straight line)
%		-argument #4 (required) is the ending point (coordinate/node) for the line
%		-argument #5 (optional) is the label for the diphthong
%----------------------------------------------------------------------
\DeclareDocumentCommand{\cardinaldiphthong}{ O{left} m O{15} m O{} }
{%
	% Error checking for #2 (cardinal vowel at diphthong starting point) - is empty?
	\tl_if_empty:nT {#2} 
		{ \PackageError{tikz-vowel:\cardinaldiphthong}
			{Cardinal~vowel~at~diphthong~starting~point~is~undefined}{} }
	% Error checking for #4 (cardinal vowel at diphthong ending point) - is empty?
	\tl_if_empty:nT {#4}
		{ \PackageError{tikz-vowel:\cardinaldiphthong}
			{Cardinal~vowel~at~diphthong~ending~point~is~undefined}{} }

	% Error checking for #2 (cardinal vowel at diphthong starting point) - is blank?
	\tl_if_blank:nT {#2} 
		{ \PackageError{tikz-vowel:\cardinaldiphthong}
			{Cardinal~vowel~at~diphthong~starting~point~is~undefined}{} }
	% Error checking for #4 (cardinal vowel at diphthong ending point) - is blank?
	\tl_if_blank:nT {#4}
		{ \PackageError{tikz-vowel:\cardinaldiphthong}
			{Cardinal~vowel~at~diphthong~ending~point~is~undefined}{} }
	
	%------------------------------------------------------------------------------------------------
	% Draw a line from cardinal vowel #2 to cardinal vowel #4
	% - put label #5 at the center point of the line
	
	% If there is no label specified (or it's blank), then draw no label at the center.
	\tl_if_blank:nTF {#5}
	{%
		\tl_gput_right:Nx \g_tikzvowel_draw_tl
			{%
				%\exp_not:N \node ( \exp_not:V \l_tikzvowel_stripped_label_tl )
				\exp_not:N \draw[diphthongLine,
									bend~#1=#3, 
									name~path=#2to#4]
									(#2) % Cardinal vowel (start)
								to
									(#4);% Cardinal vowel (end)
			}%
	}
	{% Otherwise, label is specified.  Print it at center point of line.
		% Set the token list to the string value (NOT actual macros/commands) of the label/name
		\tl_set:Nx \l_tikzvowel_stripped_label_tl { \tl_to_str:n {#5} }

		% Replace anything matching a command ( \ NAME { ) or a closing curly bracket with nothing
		% (i.e. delete macro/command-related stuff - it's not allowed for the tikz node name
		% ***WARNING***
		% This may not cover all commands... it may need to be updated or added to eventually
		% to account for additional complicated situations
		\regex_replace_all:nnN { [\\]([^\\]*?)[\{]|[\}] } {} \l_tikzvowel_stripped_label_tl
		\regex_replace_all:nnN { [\\]([^\\]*?)\s+ } {} \l_tikzvowel_stripped_label_tl
		
		\tl_gput_right:Nx \g_tikzvowel_draw_tl
			{%
				\exp_not:N \draw[diphthongLine,
									bend~#1=#3,
									name~path=\exp_not:V \l_tikzvowel_stripped_label_tl]
									(#2) % Cardinal vowel (start)
								to~
									node [diphthongLabel] {\exp_not:n {#5}}
									(#4);% Cardinal vowel (end)
			}%
	}%
}%
%----------------------------------------------------------------------
%	Diphthong from cardinal vowel to specified x,y point
%		-argument #1 (optional) is the bend of the line (left or right)
%		-argument #2 (required) is the starting point (coordinate/node) for the line
%		-argument #3 (optional) is the degree of bend in the line (0 = straight line)
%		-argument #4 (required) is the ending (X,Y) point (coordinate/node) for the line
%		-argument #5 (optional) is the label for the diphthong
%----------------------------------------------------------------------
\DeclareDocumentCommand{\cardinaltoxydiphthong}{ O{left} m O{15} D(){} O{}}
{%
	% Error checking for #4 (vowel node X,Y location) - is empty?
	\tl_if_empty:nT {#4}
		{ \PackageError{tikz-vowel:\cardinaltoxydiphthong}{Vowel~node~location~is~undefined}{} }

	% Error checking for #4 (vowel node X,Y location) - is blank?
	\tl_if_blank:nT {#4}
		{ \PackageError{tikz-vowel:\cardinaltoxydiphthong}{Vowel~node~location~is~undefined}{} }
	
	% Error checking for #3 (vowel node location) - 
	% Contains unwanted letters/numbers/characters?
	\regex_match:nnT { [^0-9\-.,\s] } { #4 }
	{%
		% Unexpected character(s) found - throw error
		\PackageError{tikz-vowel:\cardinaltoxydiphthong}
			{Diphthong~node~ending~at~(#4)~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}%
	}%
		
	% Split the values for X and Y, based on a comma
	\regex_split:nnNF { , } { #4 } \l_tikzvowel_coordinates_seq
		{%
			% No , character was found - throw error.
			\PackageError{tikz-vowel:\cardinaltoxydiphthong}
				{Diphthong~node~ending~at~(#4)~is~invalid.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}%
		}%
 	
 	% Error check - 
	% Check if less than 1 element in the sequence (this should never happen).
	\int_compare:nNnTF { \seq_count:N \l_tikzvowel_coordinates_seq } < { 1 }
	{%
 		% If less than 1, something serious occurred - throw error.
 		\PackageError{tikz-vowel:\cardinaltoxydiphthong}
			{Diphthong~node~ending~at~(#4)~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}%
 	}
 	{%
 		% Error check -
 		% Check if greater than 2 elements in the sequence
 		\int_compare:nNnTF { \seq_count:N \l_tikzvowel_coordinates_seq } > { 2 }
 		{%
 			% If greater than 2, user typed something wrong - throw error.
 			\PackageError{tikz-vowel:\cardinaltoxydiphthong}
				{Diphthong~node~ending~at~'#5'~is~invalid.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}%
 		}%
 	}%

	% Call \cardinaltoanydiphthong with the X, Y location specified
	\cardinaltoanydiphthong	[#1]
							{#2}
							[#3]
							{\seq_item:Nn \l_tikzvowel_coordinates_seq {1}}
							{\seq_item:Nn \l_tikzvowel_coordinates_seq {2}}
							[#5]
}%
%----------------------------------------------------------------------
%	Diphthong from cardinal vowel to specified x,y point
%		-argument #1 (optional) is the bend of the line (left or right)
%		-argument #2 (required) is the starting point (coordinate/node) for the line
%		-argument #3 (optional) is the degree of bend in the line (0 = straight line)
%		-argument #4 (required) is the ending X point (coordinate/node) for the line
%		-argument #5 (required) is the ending Y point (coordinate/node) for the line
%		-argument #6 (optional) is the label for the diphthong
%----------------------------------------------------------------------
\DeclareDocumentCommand{\cardinaltoanydiphthong}{ O{left} m O{15} m m O{} }
{%
	% Error checking for #2 (cardinal vowel at diphthong starting point) - is empty?
	\tl_if_empty:nT {#2} 
		{ \PackageError{tikz-vowel:\cardinaltoanydiphthong}
			{Cardinal~vowel~at~diphthong~starting~point~is~undefined}{} }
	% Error checking for #4 (vowel x-axis ending point) - is empty?
	\tl_if_empty:nT {#4}
		{ \PackageError{tikz-vowel:\cardinaltoanydiphthong}
			{Diphthong~x-axis~ending~point~is~undefined}{} }
	% Error checking for #5 (vowel y-axis ending point) - is empty?
	\tl_if_empty:nT {#5}
		{ \PackageError{tikz-vowel:\cardinaltoanydiphthong}
			{Diphthong~y-axis~ending~point~is~undefined}{} }

	% Error checking for #2 (cardinal vowel at diphthong starting point) - is blank?
	\tl_if_blank:nT {#2} 
		{ \PackageError{tikz-vowel:\cardinaltoanydiphthong}
			{Cardinal~vowel~at~diphthong~starting~point~is~undefined}{} }
	% Error checking for #4 (vowel x-axis ending point) - is blank?
	\tl_if_blank:nT {#4}
		{ \PackageError{tikz-vowel:\cardinaltoanydiphthong}
			{Diphthong~x-axis~ending~point~is~undefined}{} }
	% Error checking for #5 (vowel y-axis ending point) - is blank?
	\tl_if_blank:nT {#5}
		{ \PackageError{tikz-vowel:\cardinaltoanydiphthong}
			{Diphthong~y-axis~ending~point~is~undefined}{} }
	
	%------------------------------------------------------------------------------------------------
	% Draw a line from cardinal vowel #2 to node (#4 ,#5)
	% - put label #6 at the center point of the line
	
	% If there is no label specified (or it's blank), then draw no label at the center.
	\tl_if_blank:nTF {#6}
	{%
		\tl_gput_right:Nx \g_tikzvowel_draw_tl
			{%
				\exp_not:N \draw[diphthongLine,
									bend~#1=#3,
									name~path=#2to#4#5]
									(#2) % Cardinal vowel
								to
									(#4 ,#5);%X, Y coordinates
			}%
		
	}
	{% Otherwise, label is specified.  Print it at center point of line.
		% Set the token list to the string value (NOT actual macros/commands) of the label/name
		\tl_set:Nx \l_tikzvowel_stripped_label_tl { \tl_to_str:n {#6} }

		% Replace anything matching a command ( \ NAME { ) or a closing curly bracket with nothing
		% (i.e. delete macro/command-related stuff - it's not allowed for the tikz node name
		% ***WARNING***
		% This may not cover all commands... it may need to be updated or added to eventually
		% to account for additional complicated situations
		\regex_replace_all:nnN { [\\]([^\\]*?)[\{]|[\}] } {} \l_tikzvowel_stripped_label_tl
		\regex_replace_all:nnN { [\\]([^\\]*?)\s+ } {} \l_tikzvowel_stripped_label_tl
		
		\tl_gput_right:Nx \g_tikzvowel_draw_tl
			{%
				\exp_not:N \draw[diphthongLine,
									bend~#1=#3,
									name~path=\exp_not:V \l_tikzvowel_stripped_label_tl]
									(#2) % Cardinal vowel
								to~
									node [diphthongLabel] {\exp_not:n {#6}}
										(#4 ,#5);%X, Y coordinates
			}%
	}%
}%
%----------------------------------------------------------------------
%	Diphthong from specified x,y point to cardinal vowel
%		-argument #1 (optional) is the bend of the line (left or right)
%		-argument #2 (required) is the starting X, Y point (coordinate/node) for the line
%		-argument #3 (optional) is the degree of bend in the line (0 = straight line)
%		-argument #4 (required) is the ending point (coordinate/node) for the line
%		-argument #5 (optional) is the label for the diphthong
%----------------------------------------------------------------------
\DeclareDocumentCommand{\xytocardinaldiphthong}{ O{left} D(){} O{15} m O{} }
{%
	% Error checking for #2 (vowel node X,Y location) - is empty?
	\tl_if_empty:nT {#2}
		{ \PackageError{tikz-vowel:\xytocardinaldiphthong}{Vowel~node~location~is~undefined}{} }

	% Error checking for #2 (vowel node X,Y location) - is blank?
	\tl_if_blank:nT {#2}
		{ \PackageError{tikz-vowel:\xytocardinaldiphthong}{Vowel~node~location~is~undefined}{} }
	
	% Error checking for #3 (vowel node location) - 
	% Contains unwanted letters/numbers/characters?
	\regex_match:nnT { [^0-9\-.,\s] } { #2 }
	{%
		% Unexpected character(s) found - throw error
		\PackageError{tikz-vowel:\xytocardinaldiphthong}
			{Diphthong~node~ending~at~(#2)~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}
	}
		
	% Split the values for X and Y, based on a comma
	\regex_split:nnNF { , } { #2 } \l_tikzvowel_coordinates_seq
		{%
			% No , character was found - throw error.
			\PackageError{tikz-vowel:\xytocardinaldiphthong}
				{Diphthong~node~ending~at~(#2)~is~invalid.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}
		}
 	
 	% Error check - 
	% Check if less than 1 element in the sequence (this should never happen).
	\int_compare:nNnTF { \seq_count:N \l_tikzvowel_coordinates_seq } < { 1 }
	{%
 		% If less than 1, something serious occurred - throw error.
 		\PackageError{tikz-vowel:\xytocardinaldiphthong}
			{Diphthong~node~ending~at~(#2)~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}
 	}
 	{%
 		% Error check -
 		% Check if greater than 2 elements in the sequence
 		\int_compare:nNnTF { \seq_count:N \l_tikzvowel_coordinates_seq } > { 2 }
 		{%
 			% If greater than 2, user typed something wrong - throw error.
 			\PackageError{tikz-vowel:\xytocardinaldiphthong}
				{Diphthong~node~ending~at~'#2'~is~invalid.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}
 		}%
 	}%

	% Call \anytocardinaldiphthong with the X, Y location specified
	\anytocardinaldiphthong	[#1]
							{\seq_item:Nn \l_tikzvowel_coordinates_seq {1}}
							{\seq_item:Nn \l_tikzvowel_coordinates_seq {2}}
							[#3]
							{#4}
							[#5]
}%
%----------------------------------------------------------------------
%	Diphthong from specified x,y point to cardinal vowel
%		-argument #1 (optional) is the bend of the line (left or right)
%		-argument #2 (required) is the starting X point (coordinate/node) for the line
%		-argument #3 (required) is the starting Y point (coordinate/node) for the line
%		-argument #4 (optional) is the degree of bend in the line (0 = straight line)
%		-argument #5 (required) is the ending point (coordinate/node) for the line
%		-argument #6 (optional) is the label for the diphthong
%----------------------------------------------------------------------
\DeclareDocumentCommand{\anytocardinaldiphthong}{ O{left} m m O{15} m O{} }
{%
	% Error checking for #2 (vowel x-axis starting point) - is empty?
	\tl_if_empty:nT {#2} 
		{ \PackageError{tikz-vowel:\anytocardinaldiphthong}
			{Diphthong~x-axis~starting~point~is~undefined}{} }
	% Error checking for #3 (vowel y-axis starting point) - is empty?
	\tl_if_empty:nT {#3}
		{ \PackageError{tikz-vowel:\anytocardinaldiphthong}
			{Diphthong~y-axis~starting~point~is~undefined}{} }
	% Error checking for #5 (cardinal vowel at diphthong ending point) - is empty?
	\tl_if_empty:nT {#5}
		{ \PackageError{tikz-vowel:\anytocardinaldiphthong}
			{Cardinal~vowel~at~diphthong~ending~point~is~undefined}{} }

	% Error checking for #2 (vowel x-axis starting point) - is blank?
	\tl_if_blank:nT {#2} 
		{ \PackageError{tikz-vowel:\anytocardinaldiphthong}
			{Diphthong~x-axis~starting~point~is~undefined}{} }
	% Error checking for #3 (vowel y-axis starting point) - is blank?
	\tl_if_blank:nT {#3}
		{ \PackageError{tikz-vowel:\anytocardinaldiphthong}
			{Diphthong~y-axis~starting~point~is~undefined}{} }
	% Error checking for #5 (cardinal vowel at diphthong ending point) - is blank?
	\tl_if_blank:nT {#5}
		{ \PackageError{tikz-vowel:\anytocardinaldiphthong}
			{Cardinal~vowel~at~diphthong~ending~point~is~undefined}{} }
	
	%------------------------------------------------------------------------------------------------
	% Draw a line from node (#2 ,#3) to cardinal vowel #5
	% - put label #6 at the center point of the line

	% If there is no label specified (or it's blank), then draw no label at the center.
	\tl_if_blank:nTF {#6}
	{%
		\tl_gput_right:Nx \g_tikzvowel_draw_tl
			{%
				\exp_not:N \draw[diphthongLine,
									bend~#1=#4,
									name~path=#2#3to#5]
									(#2 ,#3) % X, Y coordinates
								to
									( #5 );% Cardinal vowel
			}%
	}
	{% Otherwise, label is specified.  Print it at center point of line.
		% Set the token list to the string value (NOT actual macros/commands) of the label/name
		\tl_set:Nx \l_tikzvowel_stripped_label_tl { \tl_to_str:n {#6} }

		% Replace anything matching a command ( \ NAME { ) or a closing curly bracket with nothing
		% (i.e. delete macro/command-related stuff - it's not allowed for the tikz node name
		% ***WARNING***
		% This may not cover all commands... it may need to be updated or added to eventually
		% to account for additional complicated situations
		\regex_replace_all:nnN { [\\]([^\\]*?)[\{]|[\}] } {} \l_tikzvowel_stripped_label_tl
		\regex_replace_all:nnN { [\\]([^\\]*?)\s+ } {} \l_tikzvowel_stripped_label_tl
		
		\tl_gput_right:Nx \g_tikzvowel_draw_tl
			{%
				\exp_not:N \draw[diphthongLine,
									bend~#1=#4,
									name~path=\exp_not:V \l_tikzvowel_stripped_label_tl]
									(#2 ,#3) % X, Y coordinates
								to~
									node [diphthongLabel] {\exp_not:n {#6}}
										( #5 );% Cardinal vowel
			}%
	}%
}%
%----------------------------------------------------------------------
%	Diphthong from specified x1,y1 point to specified x2,y2
%		-argument #1 (optional) is the bend of the line (left or right)
%		-argument #2 (required) is the starting X, Y point (coordinate/node) for the line
%		-argument #3 (optional) is the degree of bend in the line (0 = straight line)
%		-argument #4 (required) is the ending X, Y point (coordinate/node) for the line
%		-argument #5 (optional) is the label for the diphthong
%----------------------------------------------------------------------
\DeclareDocumentCommand{\xydiphthong}{ O{left} D(){} O{15} D(){} O{} }
{%
	% Error checking for #2 (vowel node X,Y location) - is empty?
	\tl_if_empty:nT {#2}
		{ \PackageError{tikz-vowel:\xydiphthong}{Vowel~diphthong~starting~location~is~undefined}{} }
	% Error checking for #4 (vowel node X,Y location) - is empty?
	\tl_if_empty:nT {#4}
		{ \PackageError{tikz-vowel:\xydiphthong}{Vowel~diphthong~ending~location~is~undefined}{} }

	% Error checking for #2 (vowel node X,Y location) - is blank?
	\tl_if_blank:nT {#2}
		{ \PackageError{tikz-vowel:\xydiphthong}{Vowel~diphthong~starting~location~is~undefined}{} }
	% Error checking for #4 (vowel node X,Y location) - is blank?
	\tl_if_blank:nT {#4}
		{ \PackageError{tikz-vowel:\xydiphthong}{Vowel~diphthong~ending~location~is~undefined}{} }
	
	% Error checking for #2 (vowel node starting location) - 
	% Contains unwanted letters/numbers/characters?
	\regex_match:nnT { [^0-9\-.,\s] } { #2 }
	{%
		% Unexpected character(s) found - throw error
		\PackageError{tikz-vowel:\xydiphthong}
			{Diphthong~node~starting~at~(#2)~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}
	}
	
	% Error checking for #4 (vowel node ending location) - 
	% Contains unwanted letters/numbers/characters?
	\regex_match:nnT { [^0-9\-.,\s] } { #4 }
	{%
		% Unexpected character(s) found - throw error
		\PackageError{tikz-vowel:\xydiphthong}
			{Diphthong~node~ending~at~(#4)~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}
	}%
		
	% Split the values for starting X and Y, based on a comma
	\regex_split:nnNF { , } { #2 } \l_tikzvowel_starting_coordinates_seq
		{%
			% No , character was found - throw error.
			\PackageError{tikz-vowel:\xydiphthong}
				{Diphthong~node~starting~at~(#2)~is~invalid.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}%
		}%
	% Split the values for ending X and Y, based on a comma
	\regex_split:nnNF { , } { #4 } \l_tikzvowel_ending_coordinates_seq
		{%
			% No , character was found - throw error.
			\PackageError{tikz-vowel:\xydiphthong}
				{Diphthong~node~ending~at~(#4)~is~invalid.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}%
		}%
 	
 	% Error check - 
	% Check if less than 1 element in the sequence (this should never happen).
	\int_compare:nNnTF { \seq_count:N \l_tikzvowel_starting_coordinates_seq } < { 1 }
	{%
 		% If less than 1, something serious occurred - throw error.
 		\PackageError{tikz-vowel:\xydiphthong}
			{Diphthong~node~starting~at~(#2)~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}%
 	}
 	{%
 		% Error check -
 		% Check if greater than 2 elements in the sequence
 		\int_compare:nNnTF { \seq_count:N \l_tikzvowel_starting_coordinates_seq } > { 2 }
 		{%
 			% If greater than 2, user typed something wrong - throw error.
 			\PackageError{tikz-vowel:\xydiphthong}
				{Diphthong~node~starting~at~'#2'~is~invalid.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}%
 		}%
 	}%
 	
 	% Error check - 
	% Check if less than 1 element in the sequence (this should never happen).
	\int_compare:nNnTF { \seq_count:N \l_tikzvowel_ending_coordinates_seq } < { 1 }
	{%
 		% If less than 1, something serious occurred - throw error.
 		\PackageError{tikz-vowel:\xydiphthong}
			{Diphthong~node~ending~at~(#4)~is~invalid.~
			Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
			Correct~syntax~is~'(X,Y)'.~
			X~and~Y~must~be~an~integer~or~decimal~value}
			{}%
 	}
 	{%
 		% Error check -
 		% Check if greater than 2 elements in the sequence
 		\int_compare:nNnTF { \seq_count:N \l_tikzvowel_ending_coordinates_seq } > { 2 }
 		{%
 			% If greater than 2, user typed something wrong - throw error.
 			\PackageError{tikz-vowel:\xydiphthong}
				{Diphthong~node~ending~at~'#4'~is~invalid.~
				Must~be~x-axis~and~y-axis~coordinates,~separated~by~a~comma.~
				Correct~syntax~is~'(X,Y)'.~
				X~and~Y~must~be~an~integer~or~decimal~value}
				{}%
 		}%
 	}%

	% Call \anydiphthong with the X, Y locations specified
	\anydiphthong	[#1]
					{\seq_item:Nn \l_tikzvowel_starting_coordinates_seq {1}}
					{\seq_item:Nn \l_tikzvowel_starting_coordinates_seq {2}}
					[#3]
					{\seq_item:Nn \l_tikzvowel_ending_coordinates_seq {1}}
					{\seq_item:Nn \l_tikzvowel_ending_coordinates_seq {2}}
					[#5]
}%
%----------------------------------------------------------------------
%	Diphthong from specified x1,y1 point to specified x2,y2
%		-argument #1 (optional) is the bend of the line (left or right)
%		-argument #2 (required) is the starting X point (coordinate/node) for the line
%		-argument #3 (required) is the starting Y point (coordinate/node) for the line
%		-argument #4 (optional) is the degree of bend in the line (0 = straight line)
%		-argument #5 (required) is the ending X point (coordinate/node) for the line
%		-argument #6 (required) is the ending Y point (coordinate/node) for the line
%		-argument #7 (optional) is the label for the diphthong
%----------------------------------------------------------------------
\DeclareDocumentCommand{\anydiphthong}{ O{left} m m O{15} m m O{} }
{%
	% Error checking for #2 (vowel x-axis starting point) - is empty?
	\tl_if_empty:nT {#2} 
		{ \PackageError{tikz-vowel:\anydiphthong}
			{Diphthong~x-axis~starting~point~is~undefined}{} }
	% Error checking for #3 (vowel y-axis starting point) - is empty?
	\tl_if_empty:nT {#3}
		{ \PackageError{tikz-vowel:\anydiphthong}
			{Diphthong~y-axis~starting~point~is~undefined}{} }
	% Error checking for #5 (vowel x-axis ending point) - is empty?
	\tl_if_empty:nT {#5} 
		{ \PackageError{tikz-vowel:\anydiphthong}
			{Diphthong~x-axis~ending~point~is~undefined}{} }
	% Error checking for #6 (vowel y-axis ending point) - is empty?
	\tl_if_empty:nT {#6}
		{ \PackageError{tikz-vowel:\anydiphthong}
			{Diphthong~y-axis~ending~point~is~undefined}{} }

	% Error checking for #2 (vowel x-axis starting point) - is blank?
	\tl_if_blank:nT {#2} 
		{ \PackageError{tikz-vowel:\anydiphthong}
			{Diphthong~x-axis~starting~point~is~undefined}{} }
	% Error checking for #3 (vowel y-axis starting point) - is blank?
	\tl_if_blank:nT {#3}
		{ \PackageError{tikz-vowel:\anydiphthong}
			{Diphthong~y-axis~starting~point~is~undefined}{} }
	% Error checking for #5 (vowel x-axis ending point) - is blank?
	\tl_if_blank:nT {#5} 
		{ \PackageError{tikz-vowel:\anydiphthong}
			{Diphthong~x-axis~ending~point~is~undefined}{} }
	% Error checking for #6 (vowel y-axis ending point) - is blank?
	\tl_if_blank:nT {#6}
		{ \PackageError{tikz-vowel:\anydiphthong}
			{Diphthong~y-axis~ending~point~is~undefined}{} }

	%------------------------------------------------------------------------------------------------
	% Draw a line from node (#2 ,#3) to node (#5 ,#6)
	% - put label #7 at the center point of the line

	% If there is no label specified (or it's blank), then draw no label at the center.
	\tl_if_blank:nTF {#7}
	{%
		\tl_gput_right:Nx \g_tikzvowel_draw_tl
			{%
				\exp_not:N \draw[diphthongLine,
									bend~#1=#4,
									name~path=#2#3to#5#6]
									(#2 ,#3) 
								to
									(#5,#6);%
			}%
	}
	{% Otherwise, label is specified.  Print it at center point of line.
		% Set the token list to the string value (NOT actual macros/commands) of the label/name
		\tl_set:Nx \l_tikzvowel_stripped_label_tl { \tl_to_str:n {#7} }

		% Replace anything matching a command ( \ NAME { ) or a closing curly bracket with nothing
		% (i.e. delete macro/command-related stuff - it's not allowed for the tikz node name
		% ***WARNING***
		% This may not cover all commands... it may need to be updated or added to eventually
		% to account for additional complicated situations
		\regex_replace_all:nnN { [\\]([^\\]*?)[\{]|[\}] } {} \l_tikzvowel_stripped_label_tl
		\regex_replace_all:nnN { [\\]([^\\]*?)\s+ } {} \l_tikzvowel_stripped_label_tl
		
		\tl_gput_right:Nx \g_tikzvowel_draw_tl
			{%
				\exp_not:N \draw[diphthongLine,
									bend~#1=#4,
									name~path=\exp_not:V \l_tikzvowel_stripped_label_tl]
									(#2 ,#3) 
								to~
									node [diphthongLabel] {\exp_not:n {#7}}
										(#5,#6);%
			}%
	}
}%
%----------------------------------------------------------------------
%
%	New tikz-vowel environment
%		-specifies sagittarial grid in background layer
%			-see \cs_tikzvowel_populate_cardinal_vowel_coordinates:
%		-allows vowel nodes (with or without a dot) in main layer
%			-see \cardinalvowel
%			-see \xyvowel
%			-see \anyvowel
%		-allows diphthong lines (with diphthong label midway in line) in main layer
%			-see \cardinaldiphthong
%			-see \cardinaltoxydiphthong
%			-see \cardinaltoanydiphthong
%			-see \xytocardinaldiphthong
%			-see \anytocardinaldiphthong
%			-see \xydiphthong
%			-see \anydiphthong
%
%----------------------------------------------------------------------
% Create a new token list to store the fixed vowel node label/name
\tl_if_exist:NF \l_tikzvowel_fix_spaces_tl
	{ \tl_new:N \l_tikzvowel_fix_spaces_tl }
%
% Create a floating point value which is the scale factor for a tikzpicture
\fp_if_exist:NF \g_tikzvowel_scale_fp
	{ \fp_new:N \g_tikzvowel_scale_fp }
%
% Create a constant for distance between label and node
\dim_const:Nn \c_tikzvowel_label_distance_dim {0.85em}%{0.25cm}%{0.1cm}%
%
% Create a constant for vertical offset of vowel label
\dim_const:Nn \c_tikzvowel_label_vertical_offset_dim {-2.2pt}%{-0.55ex}%{-0.33333ex}%{-3.5pt}%{-2.5pt}%{-2.66666pt}
%
% Create a sequence (i.e. list of tokens) to aid in separating X and Y coordinates from (X, Y) argument
\seq_if_exist:NF \l_tikzvowel_optional_arg_seq
	{ \seq_new:N \l_tikzvowel_optional_arg_seq }
%
% Create a new token list to contain all, but the 'scale=...' argument from tikzpicture argument
\tl_if_exist:NF \l_tikzvowel_remove_scale_tl
	{ \tl_new:N \l_tikzvowel_remove_scale_tl }
%
\DeclareDocumentEnvironment{tikz-vowel}{ O{default} D(){scale=1} D<>{} }
{\tikz@vowel@picture{#1}{#2}{#3}}
{\endtikz@vowel@picture}%
%
\NewEnviron{tikz@vowel@picture}[3]
{%
	% Clear all the nodes - in case a previous tikzpicture didn't
	\tl_clear:N \g_tikzvowel_nodes_tl
	% Clear all the diphthongs - in case a previous tikzpicture didn't
	\tl_clear:N \g_tikzvowel_draw_tl

	% Set the token list to the string value (NOT actual macros/commands) of the label/name
	\tl_set:Nn \l_tikzvowel_fix_spaces_tl {#2}
	
	% Check if value of #3 is 'transparency'
	% - if true, use a transparent fill/background for node labels
	\regex_match:nnTF { transparency } { #3 }
	{%
		\begin{tikzpicture}[transparency~group=knockout,#2]
	}
	{%
		\begin{tikzpicture}[#2]
	}
		% Determine the scale factor from tikzpicture keyvalues
		\pgfgettransformentries{\tikz@x@scale}{\@tempa}{\@tempa}{\tikz@y@scale}{\@tempa}{\@tempa}
		
		%Store the scale factor in a floating point variable for use elsewhere, if necessary
		\fp_gset:Nn \g_tikzvowel_scale_fp { \tikz@x@scale }
		
		% Check if value of #3 is 'transparency'
		% - if true, use a transparent fill/background for node labels
		\regex_match:nnTF { transparency } { #3 }
		{%
			\tikzset
			{%
				vowelLetter/.style=	{scale=\fp_use:N \g_tikzvowel_scale_fp,
									circle,
									fill, opacity=0, text~opacity=1, 
									inner~sep=0.5pt,
									outer~sep=0pt,},%
				vowelLabel/.style=	{scale=\fp_use:N \g_tikzvowel_scale_fp,
									circle,
									fill,opacity=0,text~opacity=1,
									label~distance=\dim_use:N \c_tikzvowel_label_vertical_offset_dim,
									node~distance=\dim_use:N \c_tikzvowel_label_distance_dim,
									inner~sep=0.5pt,
									outer~sep=0pt,},%	
				diphthongLabel/.style=	{scale=\fp_use:N \g_tikzvowel_scale_fp,
										midway,
										circle,
										fill, opacity=0, text~opacity=1,
										inner~sep=0.5pt,
										outer~sep=0pt,	},%												
			}%
		}
		{% false - No transparency setting.  Use a white fill/background for vowel labels
			\tikzset
			{%
				vowelLetter/.style=	{scale=\fp_use:N \g_tikzvowel_scale_fp,
									circle,
									fill=white,
									inner~sep=0.5pt,
									outer~sep=0pt,},%
				vowelLabel/.style=	{scale=\fp_use:N \g_tikzvowel_scale_fp,
									circle,
									fill=white,
									label~distance=\dim_use:N \c_tikzvowel_label_vertical_offset_dim,
									node~distance=\dim_use:N \c_tikzvowel_label_distance_dim,
									inner~sep=0.5pt,
									outer~sep=0pt,},
				diphthongLabel/.style=	{scale=\fp_use:N \g_tikzvowel_scale_fp,
										midway,
										circle,
										fill=white,
										inner~sep=0.5pt,
										outer~sep=0pt,},%		
			}%
		}%
		\tikzset
		{%
			vowelDot/.style=	{%scale=\fp_use:N \g_tikzvowel_scale_fp *0.5,
								anchor=base,
								inner~sep=\fp_use:N \g_tikzvowel_scale_fp *1.5pt,
								outer~sep=0pt,
								%node~distance=-20pt,
								fill,
								circle,},%
			%diphthongLine/.style=	{-{Latex[length=1.5ex*\fp_use:N \g_tikzvowel_scale_fp,
												%width=0.6em*\fp_use:N \g_tikzvowel_scale_fp]},},%
			diphthongLine/.style=	{-stealth,
									line~width=0.5pt*\fp_use:N \g_tikzvowel_scale_fp},
			double~-stealth/.style~args={##1~colored~by~##2~and~##3}{
											-stealth,line~width=##1,
											##2,
											postaction={-stealth,
														draw,
														##3,
														line~width=(##1)/1.75,
														shorten~<=(##1)/3,
														shorten~>=2*(##1)/5},},
														%line~width=(##1)/3,
														%shorten~<=(##1)/3,
														%shorten~>=2*(##1)/3},},
		}%
		
		% If picture has 'rectangle' layout
		\regex_match:nnTF { rectangle } {#1}
		{%
			\coordinate (hf) at (0,3); % the high front vertex
			\coordinate (hb) at (4,3); % the high back vertex
			\coordinate (lb) at (4,0); % the low back vertex
			\coordinate (lf) at (0,0); % the low front vertex
			
			\tl_gset:cn { g_tikzvowel_xV1_tl } { 0 }
			\tl_gset:cn { g_tikzvowel_xV2_tl } { 0 }
			\tl_gset:cn { g_tikzvowel_xV3_tl } { 0 }
			\tl_gset:cn { g_tikzvowel_xV4_tl } { 0 }
			\tl_gset:cn { g_tikzvowel_xV5_tl } { 4 }
			\tl_gset:cn { g_tikzvowel_xV6_tl } { 4 }
			\tl_gset:cn { g_tikzvowel_xV7_tl } { 4 }
			\tl_gset:cn { g_tikzvowel_xV8_tl } { 4 }
			\tl_gset:cn { g_tikzvowel_xV9_tl } { 2 }
			\tl_gset:cn { g_tikzvowel_xV10_tl } { 2 }
			\tl_gset:cn { g_tikzvowel_xV11_tl } { 2 }
			\tl_gset:cn { g_tikzvowel_xV12_tl } { 2 }
			\tl_gset:cn { g_tikzvowel_xV13_tl } { 1 }
			\tl_gset:cn { g_tikzvowel_xV14_tl } { 3 }
			\tl_gset:cn { g_tikzvowel_xV15_tl } { 2 }
			\tl_gset:cn { g_tikzvowel_xV16_tl } { 0 }	
		}
		{%
			% If picture has 'triangle' layout
			\regex_match:nnTF { triangle } {#1} 
			{%
				\coordinate (hf) at (0,3); % the high front vertex
				\coordinate (hb) at (4,3); % the high back vertex
				\coordinate (lb) at (2,0); % the low back vertex
				\coordinate (lf) at (2,0); % the low front vertex
			
				\tl_gset:cn { g_tikzvowel_xV1_tl } { 0 }
				\tl_gset:cn { g_tikzvowel_xV2_tl } { 0.66666 }
				\tl_gset:cn { g_tikzvowel_xV3_tl } { 1.33333 }
				\tl_gset:cn { g_tikzvowel_xV4_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV5_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV6_tl } { 2.66666 }
				\tl_gset:cn { g_tikzvowel_xV7_tl } { 3.33333 }
				\tl_gset:cn { g_tikzvowel_xV8_tl } { 4 }
				\tl_gset:cn { g_tikzvowel_xV9_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV10_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV11_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV12_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV13_tl } { 1.16666 }
				\tl_gset:cn { g_tikzvowel_xV14_tl } { 2.83333 }
				\tl_gset:cn { g_tikzvowel_xV15_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV16_tl } { 1.66666 }
			}
			{%
				% If picture has NEITHER `rectangle' or 'triangle' layout
				\coordinate (hf) at (0,3); % the high front vertex
				\coordinate (hb) at (4,3); % the high back vertex
				\coordinate (lb) at (4,0); % the low back vertex
				\coordinate (lf) at (2,0); % the low front vertex
			
				\tl_gset:cn { g_tikzvowel_xV1_tl } { 0 }
				\tl_gset:cn { g_tikzvowel_xV2_tl } { 0.66666 }
				\tl_gset:cn { g_tikzvowel_xV3_tl } { 1.33333 }
				\tl_gset:cn { g_tikzvowel_xV4_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV5_tl } { 4 }
				\tl_gset:cn { g_tikzvowel_xV6_tl } { 4 }
				\tl_gset:cn { g_tikzvowel_xV7_tl } { 4 }
				\tl_gset:cn { g_tikzvowel_xV8_tl } { 4 }
				\tl_gset:cn { g_tikzvowel_xV9_tl } { 2 }
				\tl_gset:cn { g_tikzvowel_xV10_tl } { 2.33333 }
				\tl_gset:cn { g_tikzvowel_xV11_tl } { 2.5 }
				\tl_gset:cn { g_tikzvowel_xV12_tl } { 2.66666 }
				\tl_gset:cn { g_tikzvowel_xV13_tl } { 1.2 }
				\tl_gset:cn { g_tikzvowel_xV14_tl } { 3.3 }
				\tl_gset:cn { g_tikzvowel_xV15_tl } { 2.8 }
				\tl_gset:cn { g_tikzvowel_xV16_tl } { 1.66666 }
			}%
		}%
			
		\draw (hf) -- (hb) -- (lb) -- (lf) -- cycle; % draws the trapezoid, rectangle, or triangle
		
		% If picture has 'plain' layout
		\regex_match:nnF { plain } {#1}
		{%
			% Check if tikz-vowel arguments contain 'three'
			\regex_match:nnTF { three } {#1}
			{%
				\draw ($(hf)!0.5!(lf)$) -- ($(hb)!0.5!(lb)$); % the mid line (horizontal)
			}
			{% Does not contain 'three'
				\draw ($(hf)!1/3!(lf)$) -- ($(hb)!1/3!(lb)$); % the high-mid line (horizontal)
				\draw ($(hf)!2/3!(lf)$) -- ($(hb)!2/3!(lb)$); % the low-mid line (horizontal)
							
				% Check if tikz-vowel arguments contain 'standard'
				\regex_match:nnTF { standard } {#1}
				{%
					\coordinate (hf56lf) at ($(hf)!5/6!(lf)$);%
					\coordinate (hb56lb) at ($(hb)!5/6!(lb)$);%
					% the left line (vertical)
					\draw ($(hf)!1/4!(hb)$) -- ($(hf56lf)!0.5!(hb56lb)$);%
					% the right line (vertical)
					\draw ($(hf)!3/4!(hb)$) -- ($(hf56lf)!0.5!(hb56lb)$);%
					% the center line (vertical)
					\draw ($(hf)!0.5!(hb)$) -- ($(hf56lf)!0.5!(hb56lb)$);%
				}%
				{%
					\regex_match:nnF { simple } {#1}
					{
						\draw ($(hf)!0.5!(hb)$) -- ($(lf)!0.5!(lb)$); % the center line (vertical)
					}%
				}%
			}%
		}%
		
		% Populate the tikzpicture with coordinates for cardinal vowels
		\cs_tikzvowel_populate_cardinal_vowel_coordinates:%
		
		

		%%%%%%%%%%%%%%
		% Body the environment - provided via `environ' package
		%%%%%%%%%%%%%%
		\BODY
		%%%%%%%%%%%%%%
		
		% If diagram uses (only) top labels
		\regex_match:nnTF { top[\s]labels } {#1}
		{%
			% Draw top labels
			\cs_tikzvowel_draw_top_labels:%
		}%
		{%
			% If diagram uses (only) side labels
			\regex_match:nnTF { side[\s]labels } {#1}
			{%
				% Draw side labels
				\cs_tikzvowel_draw_side_labels:%
			}%
			{%
				% If diagram uses ALL labels
				\regex_match:nnTF { labels } {#1}
				{%
					% Draw top labels
					\cs_tikzvowel_draw_top_labels:%
					% Draw side labels
					\cs_tikzvowel_draw_side_labels:%
				}%
				{%
					% DIAGRAM USES NO LABELS -- THIS IS DEFAULT
				}%
			
			}%
			%Top labels
			%\node[labels,labels top] (FrontLabel) at (0, 3.65) {Front};
			%\node[labels,labels top] (CentralLabel) at (2, 3.65) {Central};
			%\node[labels,labels top] (BackLabel) at (4, 3.65) {Back};
			%Left side labels
			%\node[labels,labels side] (CloseLabel) at (-0.65, 3) {Close};
			%\node[labels,labels side] (ClosemidLabel) at (-0.65, 2) {Close-mid};
			%\node[labels,labels side] (OpenmidLabel) at (-0.65, 1) {Open-mid};
			%\node[labels,labels side] (OpenLabel) at (-0.65, 0) {Open};
		}%

		% Put all the nodes which were created into the output stream
		\tl_use:N \g_tikzvowel_nodes_tl
		% Put all the diphthongs which were created into the output stream
		\tl_use:N \g_tikzvowel_draw_tl
		
		% Clear all the nodes
		\tl_clear:N \g_tikzvowel_nodes_tl
		% Clear all the diphthongs
		\tl_clear:N \g_tikzvowel_draw_tl

		% Clear all token list, integer, floating point, and sequence variables
		% (just to avoid any potential problems with another picture)
		\tl_clear:N \l_tikzvowel_update_tl
		\tl_clear:N \l_tikzvowel_temp_tl
		\tl_clear:N \l_tikzvowel_temp_XY_remove_comma_tl
		\tl_clear:N \l_tikzvowel_stripped_label_tl
		\int_zero:N \l_tikzvowel_counter_int
		\int_zero:N \l_tikzvowel_cardinal_vowel_number_int
		\seq_clear:N \l_tikzvowel_coordinates_seq
		\seq_clear:N \l_tikzvowel_starting_coordinates_seq
		\seq_clear:N \l_tikzvowel_ending_coordinates_seq
		\tl_clear:N \l_tikzvowel_fix_spaces_tl
		\fp_zero:N \g_tikzvowel_scale_fp
		\seq_clear:N \l_tikzvowel_optional_arg_seq
		\tl_clear:N \l_tikzvowel_remove_scale_tl

	\end{tikzpicture}%
}%
%
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%	VOWEL LABEL styles
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%
%----------------------------------------------------------------------
%	Set the vowel label background color to #2
%		-argument #1 (required) is the vowel name
%		-argument #2 (required) is value to set as bg color
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelbgcolor}{ m m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {fill} {#2}
}
%
%----------------------------------------------------------------------
%	Set the vowel label font color to #2
%		-argument #1 (required) is the vowel name
%		-argument #2 (required) is value to set as font color
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelfontcolor}{ m m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {text} {#2}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border shape to a rectangle
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelrectangle}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {shape} {rectangle}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border shape to an ellipse
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelellipse}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {shape} {ellipse}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border shape to a coordinate
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelcoordinate}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {shape} {coordinate}
}
%
%----------------------------------------------------------------------
%	Create the vowel label border 
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelborder}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {draw} {}
}
%
%----------------------------------------------------------------------
%	Create/Set the vowel label border on and color to #2
%		-argument #1 (required) is the vowel name
%		-argument #2 (required) is value to set as border color
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelbordercolor}{ m m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {draw} {#2}
}
%
%----------------------------------------------------------------------
%	Set the vowel label background padding to #2
%		-argument #1 (required) is the vowel name
%		-argument #2 (required) is value to set as padding length/width
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelbgpadding}{ m m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {inner~sep} {#2}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border line thickness/width to #2
%		-argument #1 (required) is the vowel name
%		-argument #2 (required) is value to set as border line thickness/width
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelborderwidth}{ m m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {line~width} {#2}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border line thickness/width to ultra thin
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelborderultrathin}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {ultra~thin} {}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border line thickness/width to very thin
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelborderverythin}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {very~thin} {}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border line thickness/width to thin
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelborderthin}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {thin} {}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border line thickness/width to semithick
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelbordersemithick}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {semithick} {}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border line thickness/width to thick
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelborderthick}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {thick} {}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border line thickness/width to very thick
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelborderverythick}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {very~thick} {}
}
%
%----------------------------------------------------------------------
%	Set the vowel label border line thickness/width to ultra thick
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelborderultrathick}{ m }
{
	\cs_tikzvowel_set_vowel_label_options:nnn {#1} {ultra~thick} {}
}
%
%----------------------------------------------------------------------
%	Set vowel label tikz option (to value, if specified)
%		-argument #1 (required) is the vowel name
%		-argument #2 (required) is the TikZ option
%		-argument #3 (optional) is the TikZ option value
%----------------------------------------------------------------------
\DeclareDocumentCommand{\settikzvowellabel}{ m m g }
{%
	\IfNoValueTF{#3}
	{%
		\cs_tikzvowel_set_vowel_label_options:nnn {#1} {#2} {}
	}
	{%
		\cs_tikzvowel_set_vowel_label_options:nnn {#1} {#2} {#3}
	}
}
%
%----------------------------------------------------------------------
%	Set the vowel label options to modify its appearance
%		-argument #1 (required) is the vowel name
%		-argument #2 (required) is (tikz) option/property to set
%		-argument #3 (required) is value to set the (tikz) option/property to
%----------------------------------------------------------------------
\cs_new:Nn \cs_tikzvowel_set_vowel_label_options:nnn
{%	
	% Error checking for \g_tikzvowel_nodes_tl - is empty?
	\tl_if_empty:nT \g_tikzvowel_nodes_tl
		{%
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_options:nnn}
				{No~vowels~exist!}
				{}%
		}%

	% Error checking for \g_tikzvowel_nodes_tl - is blank?
	\tl_if_blank:nT \g_tikzvowel_nodes_tl 
		{%
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_options:nnn}
				{No~vowels~exist!}
				{}%
		}%
		
	% Checking for #3 (tikz) option - is empty/blank?
	\tl_if_blank:nTF {#3} 
	{% Assume there is no value, only include the option (e.g. circle, rectangle, etc.)
		\tl_set:Nn \l_tikzvowel_update_tl { ,#2 }
	}
	{% There is a value, so set property equal to the option/property
		\tl_set:Nn \l_tikzvowel_update_tl { ,#2=#3 }
	}%

	\tl_set_eq:NN \l_tikzvowel_temp_tl \g_tikzvowel_nodes_tl
	% Check for 'center' (or no location specified) version first
	\regex_match:nVTF { \(#1\)\[vowelLetter.*?\] } \l_tikzvowel_temp_tl
	{%
		% Replace the vowel label/name properties with an updated version containing
		% the new, appended property (and value, if applicable)
		\regex_replace_once:nnNF { (\(#1\)\[vowelLetter.*?)\] }
									{ \1\u{l_tikzvowel_update_tl}\] }
									\l_tikzvowel_temp_tl
		{% Unexpected character(s) found - throw error
			\PackageError{tikz-vowel:cs_tikzvowel_set_label_options:nnn}
				{Unexpected~error~with~vowel~label/name~'#1'}
				{}%
		}%
	}
	{% No 'center' (or no location specified) version found
		\regex_match:nVTF { =of\s#1.*?\] } \l_tikzvowel_temp_tl
		{%
			% Replace the vowel label/name properties with an updated version containing
			% the new, appended property (and value, if applicable)
			\regex_replace_once:nnNF { (=of\s#1.*?)\] }
										{ \1\u{l_tikzvowel_update_tl}\] }
										\l_tikzvowel_temp_tl
			{% Unexpected character(s) found - throw error
				\PackageError{tikz-vowel:cs_tikzvowel_set_label_options:nnn}
					{Unexpected~error~with~vowel~label/name~'#1'}
					{}%
			}%
		}
		{% No valid diphthong exists - throw an error
			\PackageError{tikz-vowel:cs_tikzvowel_set_label_options:nnn}
				{No~vowel~with~label/name~'#1'~found}
				{}%
		}%
	}%
	
	% Set the global vowel token list to the updated, temporary token list
	\tl_gset_eq:NN \g_tikzvowel_nodes_tl \l_tikzvowel_temp_tl
	% Clear the temporary token list, to be safe
	\tl_clear:N \l_tikzvowel_temp_tl
	% Clear the update token list, to be safe
	\tl_clear:N \l_tikzvowel_update_tl
}%
%
%
%----------------------------------------------------------------------
%	Set the vowel node (marker) color
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelmarkercolor}{ m m }
{%
	\cs_tikzvowel_set_vowel_node_options:nnn {#1} {fill} {#2}
}%
%
%----------------------------------------------------------------------
%	Set the vowel node (marker) color
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelmarkerborder}{ m }
{%
	\cs_tikzvowel_set_vowel_node_options:nnn {#1} {draw} {}
}%
%
%----------------------------------------------------------------------
%	Set the vowel node (marker) color
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setvowelmarkerbordercolor}{ m m }
{%
	\cs_tikzvowel_set_vowel_node_options:nnn {#1} {draw} {#2}
}%
%
%----------------------------------------------------------------------
%	Set any TikZ option/value for the vowel marker/dot
%		-argument #1 (required) - the vowel label/name
%		-argument #2 (required) - the TikZ option
%		-argument #3 (optional) - the TikZ option's value
%----------------------------------------------------------------------
\DeclareDocumentCommand{\settikzvowelmarker}{ m m g }
{%
	\IfNoValueTF{#3}
	{%
		\cs_tikzvowel_set_vowel_node_options:nnn {#1} {#2} {}
	}
	{%
		\cs_tikzvowel_set_vowel_node_options:nnn {#1} {#2} {#3}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the vowel node options to modify its appearance
%		-argument #1 (required) is the vowel name
%		-argument #2 (required) is (tikz) option/property to set
%		-argument #3 (required) is value to set the (tikz) option/property to
%----------------------------------------------------------------------
\cs_new:Nn \cs_tikzvowel_set_vowel_node_options:nnn
{%	
	% Error checking for \g_tikzvowel_nodes_tl - is empty?
	\tl_if_empty:nT \g_tikzvowel_nodes_tl
		{%
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_options:nnn}
				{No~vowels~exist!}
				{}%
		}%

	% Error checking for \g_tikzvowel_nodes_tl - is blank?
	\tl_if_blank:nT \g_tikzvowel_nodes_tl 
		{%
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_options:nnn}
				{No~vowels~exist!}
				{}%
		}%
		
	% Checking for #3 (tikz) option - is empty/blank?
	\tl_if_blank:nTF {#3} 
	{% Assume there is no value, only include the option (e.g. circle, rectangle, etc.)
		\tl_set:Nn \l_tikzvowel_update_tl { ,#2 }
	}
	{% There is a value, so set property equal to the option/property
		\tl_set:Nn \l_tikzvowel_update_tl { ,#2=#3 }
	}%

	\tl_set_eq:NN \l_tikzvowel_temp_tl \g_tikzvowel_nodes_tl
	% Check for 'center' (or no location specified) version first
	\regex_match:nVTF { \(#1\)\[vowelLetter.*?\] } \l_tikzvowel_temp_tl
	{%
		\PackageError{tikz-vowel:cs_tikzvowel_set_vowel_node_options:nnn}
				{Vowel~label/name~'#1'~is~only~a~label.~You~cannot~modify~its~dot/marker}
				{}%
	}
	{% No 'center' (or no location specified) version found
		\regex_match:nVTF { \(#1\)\[vowelDot, } \l_tikzvowel_temp_tl
		{%
			% Replace the vowel label/name properties with an updated version containing
			% the new, appended property (and value, if applicable)
			\regex_replace_once:nnNF { (\(#1\)\[vowelDot), }
										{ \1\u{l_tikzvowel_update_tl}, }
										\l_tikzvowel_temp_tl
			{% Unexpected character(s) found - throw error
				\PackageError{tikz-vowel:cs_tikzvowel_set_label_options:nnn}
					{Unexpected~error~with~vowel~label/name~'#1'}
					{}%
			}%
		}
		{% No valid diphthong exists - throw an error
			\PackageError{tikz-vowel:cs_tikzvowel_set_label_options:nnn}
				{No~vowel~with~label/name~'#1'~found}
				{}%
		}%
	}%
	
	% Set the global vowel token list to the updated, temporary token list
	\tl_gset_eq:NN \g_tikzvowel_nodes_tl \l_tikzvowel_temp_tl
	% Clear the temporary token list, to be safe
	\tl_clear:N \l_tikzvowel_temp_tl
	% Clear the update token list, to be safe
	\tl_clear:N \l_tikzvowel_update_tl
}%
%
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%	DIPHTHONG line styles
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%
%----------------------------------------------------------------------
%	Set the vowel node (marker) color
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongborder}{ m m g }
{%
	\IfNoValueTF{#3}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {double} {#2}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {double} {#3}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the vowel node (marker) color
%		-argument #1 (required) is the vowel name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongcolorborderwidth}{ m m m m }
{%
	% #4 is line width
	% #2 is border
	% #3 is inner color
	%
	\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {double~-stealth} {#4~colored~by~#3~and~#2}
	
	%double~-stealth/.style~args={##1~colored~by~##2~and~##3}
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line color
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (required) 
%					EITHER		1) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%					OR			2) the line color
%		-argument #3 (optional) 
%								the line color
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1) + line color (#2)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2) + line color (#3)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthonglinecolor}{ m m g }
{%
	\IfNoValueTF{#3}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {draw} {#2}
	}%
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {draw} {#3}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line thickness/width to specified thickness
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (required) 
%					EITHER		1) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%					OR			2) the line thickness/width
%		-argument #3 (optional) 
%								the line thickness/width
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1) + line thickness/width (#2)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2) + line thickness/width (#3)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthonglinewidth}{ m m g }
{%
	\IfNoValueTF{#3}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {line~width} {#2}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {line~width} {#3}
	}%
}
%
%----------------------------------------------------------------------
%	Set the diphthong line thickness/width to ultra thick
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (optional) 
%								the ending vowel label/name
%								(either cardinal vowel or Y coordinate
%									which was used when creating the vowel)
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongultrathick}{ m g }
{%
	\IfNoValueTF{#2}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {ultra~thick} {}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {ultra~thick} {}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line thickness/width to very thick
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (optional) 
%								the ending vowel label/name
%								(either cardinal vowel or Y coordinate
%									which was used when creating the vowel)
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongverythick}{ m g }
{%
	\IfNoValueTF{#2}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {very~thick} {}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {very~thick} {}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line thickness/width to thick
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (optional) 
%								the ending vowel label/name
%								(either cardinal vowel or Y coordinate
%									which was used when creating the vowel)
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongthick}{ m g }
{%
	\IfNoValueTF{#2}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {thick} {}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {thick} {}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line thickness/width to semi-thick
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (optional) 
%								the ending vowel label/name
%								(either cardinal vowel or Y coordinate
%									which was used when creating the vowel)
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongsemithick}{ m g }
{%
	\IfNoValueTF{#2}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {semithick} {}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {semithick} {}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line thickness/width to thin
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (optional) 
%								the ending vowel label/name
%								(either cardinal vowel or Y coordinate
%									which was used when creating the vowel)
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongthin}{ m g }
{%
	\IfNoValueTF{#2}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {thin} {}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {thin} {}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line thickness/width to very thin
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (optional) 
%								the ending vowel label/name
%								(either cardinal vowel or Y coordinate
%									which was used when creating the vowel)
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongverythin}{ m g }
{%
	\IfNoValueTF{#2}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {very~thin} {}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {very~thin} {}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line thickness/width to ultra thin
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (optional) 
%								the ending vowel label/name
%								(either cardinal vowel or Y coordinate
%									which was used when creating the vowel)
%
%		Argument structure allows for either:
%			1)	identifying the diphthong by label/name (#1)
%					(if it was labeled when creating the diphthong)
%
%			2)	identifying the starting vowel (#1) and ending vowel (#2)
%					(if no label was used when creating the diphthong)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthongultrathin}{ m g }
{%
	\IfNoValueTF{#2}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {ultra~thin} {}
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {ultra~thin} {}
	}%
}%
%
%----------------------------------------------------------------------
%	Set any TikZ option/value for the diphthong line
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(if #2, then use either cardinal vowel or X,Y coordinate
%									which was used when creating the vowel)
%		-argument #2 (required) 
%					EITHER		1) the ending vowel label/name
%									(if #1, then use either cardinal vowel or X,Y coordinate
%									which was used when creating the vowel)
%					OR			2) the TikZ option
%									(if two arguments given and first argument is diphthong label/name)
%
%		-argument #3 (optional) 
%					EITHER		1) the TikZ option
%									(if 3 arguments given and first and second argumenst
%									are the starting and ending X,Y coordinates of diphthong)
%					OR			2) the TikZ option's value 
%									(if three arguments given and first argument is diphthong label/name)
%
%		-argument #4 (optional) - the TikZ option's value (if 3 arguments given)
%----------------------------------------------------------------------
\DeclareDocumentCommand{\settikzdiphthong}{ m m g g }
{%
	\IfNoValueTF{#4}
	{%
		\IfNoValueTF{#3}
		{%
			\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {#2} {}
		}
		{%
			\cs_tikzvowel_set_diphthong_options:nnnn {#1} {} {#2} {#3}
		}%
	}
	{%
		\cs_tikzvowel_set_diphthong_options:nnnn {#1} {#2} {#3} {#4}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line options to modify its appearance
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (required) 
%					EITHER		1) the ending vowel label/name
%								(use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%					OR			2) leave it empty, if the diphthong label/name is used
%		-argument #3 (required) is (tikz) option/property to set
%		-argument #4 (required) is value to set the (tikz) option/property to
%----------------------------------------------------------------------
\cs_new:Nn \cs_tikzvowel_set_diphthong_options:nnnn
{%	
	% Error checking for diphthong token list - is empty?
	\tl_if_empty:nT \g_tikzvowel_draw_tl
		{%
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_options:nn}
				{No~diphthongs~exist!}
				{}%
		}%

	% Error checking for diphthong token list - is blank?
	\tl_if_blank:nT \g_tikzvowel_draw_tl 
		{%
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_options:nn}
				{No~diphthongs~exist!}
				{}%
		}%

	% If no value for #4, assume there is a property with no value
	\tl_if_blank:nTF {#4}
	{% Assume there is no value, only include the option (e.g. circle, rectangle, etc.)
		\tl_set:Nn \l_tikzvowel_update_tl { ,#3 }
	}
	{% There is a value, so set property = value
		\tl_set:Nn \l_tikzvowel_update_tl { ,#3=#4 }
	}%
	
	% Set temporary token list equal to the global diphthong token list
	\tl_set_eq:NN \l_tikzvowel_temp_tl \g_tikzvowel_draw_tl

	% If no value for #2, assume that diphthong label/name is use (NOT X, Y coordinates)
	\tl_if_blank:nTF {#2}
	{%
		% Check to make sure a valid diphthong exists
		\regex_match:nVTF { \[diphthongLine.*?name\s path=#1.*?\] } \l_tikzvowel_temp_tl
		{%
			% Replace the diphthong line properties with an updated version containing
			% the new, appended property (and value, if applicable)
			\regex_replace_once:nnNF { (\[diphthongLine,.*?name\s path=#1.*?)\] }
										{ \1\u{l_tikzvowel_update_tl}\] }
										\l_tikzvowel_temp_tl
			{% Unexpected character(s) found - throw error
				\PackageError{tikz-vowel:\cs_tikzvowel_set_diphthong_options:nnn}
					{Unexpected~error~with~diphthong~'#1'}
					{}%
			}%
		}
		{% No valid diphthong exists - throw an error
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_options:nnnn}
				{No~diphthong~'#1'~found}
				{}%
		}%
	}
	{% Value for #2, assume that X, Y coordinates (or cardinal vowel name) (NOT diphthong label/name)
		% Create temporary token list which removes commas from diphthong 'name path'
		\tl_set:Nn \l_tikzvowel_temp_XY_remove_comma_tl {#1to#2}
		\regex_replace_all:nnN { , } { } \l_tikzvowel_temp_XY_remove_comma_tl

		% Check to make sure a valid diphthong exists
		\regex_match:xVTF { \exp_not:N \[ diphthongLine.*?name \exp_not:N \s path= \exp_not:V \l_tikzvowel_temp_XY_remove_comma_tl .*? \exp_not:N \] } \l_tikzvowel_temp_tl
		{%
			% Replace the diphthong line properties with an updated version containing
			% the new, appended property (and value, if applicable)
			\regex_replace_once:xnNF { (\exp_not:N \[diphthongLine.*?name\exp_not:N \s path=\exp_not:V \l_tikzvowel_temp_XY_remove_comma_tl.*?)\exp_not:N \] }
										{ \1\u{l_tikzvowel_update_tl}\] }
										\l_tikzvowel_temp_tl
			{% Unexpected character(s) found - throw error
				\PackageError{tikz-vowel:\cs_tikzvowel_set_diphthong_options:nnn}
					{Unexpected~error~with~diphthong~starting~at~'#1'~
						and~ending~at~'#2'}
					{}%
			}%
		}
		{% No valid diphthong exists - throw an error
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_options:nnnn}
				{No~diphthong~starting~at~'#1'~and~ending~at~'#2'~found}
				{}%
		}%
	}

	% Set the global diphthong token list to the updated, temporary token list
	\tl_gset_eq:NN \g_tikzvowel_draw_tl \l_tikzvowel_temp_tl
	% Clear the temporary token list, to be safe
	\tl_clear:N \l_tikzvowel_temp_tl
	% Clear the update token list, to be safe
	\tl_clear:N \l_tikzvowel_update_tl
}%
%
%
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%	DIPHTHONG label styles
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%
%----------------------------------------------------------------------
%	Set the diphthong label background color
%		-argument #1 (required) - the diphthong label/name
%		-argument #2 (required) - the new background color for label
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthonglabelbgcolor}{ m m }
{%
	\cs_tikzvowel_set_diphthong_label_options:nnn {#1} {fill} {#2}
}%
%
%----------------------------------------------------------------------
%	Set the diphthong label border color
%		-argument #1 (required) - the diphthong label/name
%		-argument #2 (required) - the new border color for label
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthonglabelbordercolor}{ m m }
{%
	\cs_tikzvowel_set_diphthong_label_options:nnn {#1} {draw} {#2}
}%
%
%----------------------------------------------------------------------
%	Set the diphthong label with a border 
% 		(default is either black OR the 'draw' color of the tikzpicture)
%		-argument #1 (required) - the diphthong label/name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthonglabelborder}{ m }
{%
	\cs_tikzvowel_set_diphthong_label_options:nnn {#1} {draw} {}
}%
%
%----------------------------------------------------------------------
%	Set the diphthong label text color
%		-argument #1 (required) - the diphthong label/name
%		-argument #2 (required) - the new text color for label
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthonglabelcolor}{ m m }
{%
	\cs_tikzvowel_set_diphthong_label_options:nnn {#1} {text} {#2}
}%
%
%----------------------------------------------------------------------
%	Set the diphthong label background shape with rounded corners
%		(default background is circle and this has no effect)
%		(if background shape has been changed, e.g. to rectangle, this option will apply)
%		-argument #1 (required) - the diphthong label/name
%----------------------------------------------------------------------
\DeclareDocumentCommand{\setdiphthonglabelroundedcorners}{ m }
{%
	\cs_tikzvowel_set_diphthong_label_options:nnn {#1} {rounded~corners}
}%
%
%----------------------------------------------------------------------
%	Set any TikZ option/value for the diphthong label
%		-argument #1 (required) - the diphthong label/name
%		-argument #2 (required) - the TikZ option
%		-argument #3 (optional) - the TikZ option's value
%----------------------------------------------------------------------
\DeclareDocumentCommand{\settikzdiphthonglabel}{ m m g }
{%
	\IfNoValueTF{#3}
	{%
		\cs_tikzvowel_set_diphthong_label_options:nnn {#1} {#2} {}
	}
	{%
		\cs_tikzvowel_set_diphthong_label_options:nnn {#1} {#2} {#3}
	}%
}%
%
%----------------------------------------------------------------------
%	Set the diphthong line options to modify its appearance
%		-argument #1 (required) 
%					EITHER		1) the diphthong label/name
%					OR			2) the starting vowel label/name
%								(use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%		-argument #2 (required) 
%					EITHER		1) the ending vowel label/name
%								(use either cardinal vowel or X coordinate
%									which was used when creating the vowel)
%					OR			2) leave it empty, if the diphthong label/name is used
%		-argument #3 (required) is (tikz) option/property to set
%		-argument #4 (required) is value to set the (tikz) option/property to
%----------------------------------------------------------------------
\cs_new:Nn \cs_tikzvowel_set_diphthong_label_options:nnn
{%	
	% Error checking for diphthong token list - is empty?
	\tl_if_empty:nT \g_tikzvowel_draw_tl
		{%
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_label_options:nn}
				{No~diphthongs~exist!}
				{}%
		}%

	% Error checking for diphthong token list - is blank?
	\tl_if_blank:nT \g_tikzvowel_draw_tl 
		{%
			\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_label_options:nn}
				{No~diphthongs~exist!}
				{}%
		}%

	% If no value for #4, assume there is a property with no value
	\tl_if_blank:nTF {#3}
	{% Assume there is no value, only include the option (e.g. circle, rectangle, etc.)
		\tl_set:Nn \l_tikzvowel_update_tl { ,#2 }
	}
	{% There is a value, so set property = value
		\tl_set:Nn \l_tikzvowel_update_tl { ,#2=#3 }
	}%
	
	% Set temporary token list equal to the global diphthong token list
	\tl_set_eq:NN \l_tikzvowel_temp_tl \g_tikzvowel_draw_tl

	% Check to make sure a valid diphthong exists
	\regex_match:nVTF { \[diphthongLabel.*?\]\{.*?#1.*?\} } \l_tikzvowel_temp_tl
	{%
		% Replace the diphthong line properties with an updated version containing
		% the new, appended property (and value, if applicable)
		\regex_replace_once:nnNF { (\[diphthongLabel.*?)(\]\{.*?#1.*?\}) }
									{ \1\u{l_tikzvowel_update_tl}\2 }
									\l_tikzvowel_temp_tl
		{% Unexpected character(s) found - throw error
			\PackageError{tikz-vowel:\cs_tikzvowel_set_diphthong_label_options:nnn}
				{Unexpected~error~with~diphthong~'#1'}
				{}%
		}%
	}
	{% No valid diphthong exists - throw an error
		\tl_show_analysis:N \l_tikzvowel_temp_tl
		\PackageError{tikz-vowel:cs_tikzvowel_set_diphthong_label_options:nnnn}
			{No~diphthong~'#1'~found}
			{}%
	}%

	% Set the global diphthong token list to the updated, temporary token list
	\tl_gset_eq:NN \g_tikzvowel_draw_tl \l_tikzvowel_temp_tl
	% Clear the temporary token list, to be safe
	\tl_clear:N \l_tikzvowel_temp_tl
	% Clear the update token list, to be safe
	\tl_clear:N \l_tikzvowel_update_tl
}%
%
%