Add explanatory comments; fix odk upload error

app/models/forms/export.rb

@@ -78,9 +78,14 @@ def to_xls
 
       group_depth = 1 # assume base level
       repeat_depth = 1
+      option_sets_used = []
+
+      # Define the below "index modifiers" which keep track of the line of the spreadsheet we are writing to.
+        # The for loop below (tracked by index i) loops through the list of form items, and so the index does not take into account rows that we need to write for when groups end. In XLSForm, these are written to a row all to themselves.
+        # This causes the index i to be de-synchronized with the row of the spreadsheet that we are writing to.
+        # Hence, we push to the row (i + index_mod)
       index_mod = 1 # start at row index 1
       choices_index_mod = 0
-      option_sets_used = []
 
       @form.preordered_items.each_with_index do |q, i|
         # did one or more groups just end?
@@ -115,6 +120,9 @@ def to_xls
           # do we have an option set?
           if q.option_set_id.present?
             os = OptionSet.find(q.option_set_id)
+
+            # include leading space to respect XLSForm format
+            # question name should be followed by the option set name (if applicable) separated by a space
             os_name = " #{os.name}"
             os_already_logged = option_sets_used.include?(q.option_set_id)
 
@@ -141,7 +149,7 @@ def to_xls
           qtype_converted = QTYPE_TO_XLS[q.qtype_name]
 
           type_to_push = "#{qtype_converted}#{os_name}"
-          code_to_push = "#{q.full_dotted_rank}_#{q.code}"
+          code_to_push = "#{q.code}_#{q.full_dotted_rank}"
 
           # Write the question row
           questions.row(i + index_mod).push(type_to_push, code_to_push, q.name, q.required.to_s)
@@ -199,11 +207,6 @@ def name(qing)
       end
     end
 
-    def to_number(value)
-      return if value.blank?
-      (value.to_f % 1).positive? ? value.to_f : value.to_i
-    end
-
     # Takes an array of conditions and outputs a single string
     # concatenates by either "and" or "or" depending on form settings
     def conditions_to_xls(conditions, true_if)