diff --git a/mathics/builtin/box/layout.py b/mathics/builtin/box/layout.py
index b5bc7e9d9..9908fcc74 100644
--- a/mathics/builtin/box/layout.py
+++ b/mathics/builtin/box/layout.py
@@ -203,11 +203,11 @@ class InterpretationBox(BoxExpression):
     summary_text = "box associated to an input expression"
 
     def eval_to_expression(boxexpr, form, evaluation):
-        """ToExpression[boxexpr_IntepretationBox, form___]"""
+        """ToExpression[boxexpr_InterpretationBox, form___]"""
         return boxexpr.elements[1]
 
     def eval_display(boxexpr, evaluation):
-        """DisplayForm[boxexpr_IntepretationBox]"""
+        """DisplayForm[boxexpr_InterpretationBox]"""
         return boxexpr.elements[0]
 
 
diff --git a/mathics/builtin/datentime.py b/mathics/builtin/datentime.py
index 577e78a95..d0a2aebb7 100644
--- a/mathics/builtin/datentime.py
+++ b/mathics/builtin/datentime.py
@@ -1201,12 +1201,6 @@ class TimeZone(Predefined):
 
     summary_text = "gets the default time zone"
 
-    def eval(self, lhs, rhs, evaluation):
-        "lhs_ = rhs_"
-
-        self.assign(lhs, rhs, evaluation)
-        return rhs
-
     def evaluate(self, evaluation) -> Real:
         return self.value
 
diff --git a/mathics/builtin/files_io/files.py b/mathics/builtin/files_io/files.py
index 3248ba826..9efb0e43a 100644
--- a/mathics/builtin/files_io/files.py
+++ b/mathics/builtin/files_io/files.py
@@ -1354,6 +1354,8 @@ class Find(Read):
      = ...
     """
 
+    rules = {}
+
     options = {
         "AnchoredSearch": "False",
         "IgnoreCase": "False",
diff --git a/mathics/core/definitions.py b/mathics/core/definitions.py
index 0308f5312..1d449e063 100644
--- a/mathics/core/definitions.py
+++ b/mathics/core/definitions.py
@@ -17,6 +17,7 @@
 from mathics.core.element import fully_qualified_symbol_name
 from mathics.core.expression import Expression
 from mathics.core.load_builtin import definition_contribute, mathics3_builtins_modules
+from mathics.core.pattern import BasePattern, ExpressionPattern
 from mathics.core.symbols import Atom, Symbol, strip_context
 from mathics.core.systemsymbols import SymbolGet
 from mathics.core.util import canonic_filename
@@ -725,25 +726,137 @@ def get_history_length(self):
 
 
 def get_tag_position(pattern, name) -> Optional[str]:
+    """
+    Determine the position of a pattern in
+    the definition of the symbol ``name``
+    """
+    blanks = (
+        "System`Blank",
+        "System`BlankSequence",
+        "System`BlankNullSequence",
+    )
+
+    def strip_pattern_name_and_condition(pat: BasePattern) -> ExpressionPattern:
+        """
+        In ``Pattern[name_, pattern_]`` and
+        ``Condition[pattern_, cond_]``
+        the tag is determined by pat.
+        This function strips it to ensure that
+        ``pat`` does not have that form.
+        """
+
+        # Is "pat" as ExpressionPattern or an AtomPattern?
+        # Note: the below test could also be on ExpressionPattern or
+        # AtomPattern, but using hasattr is more flexible if more
+        # kinds of patterns are added.
+        if not hasattr(pat, "head"):
+            return pat
+
+        # We have to use get_head_name() below because
+        # pat can either SymbolCondition or <AtomPattern: System`Condition>.
+        # In the latter case, comparing to SymbolCondition is not sufficient.
+        if pat.get_head_name() == "System`Condition":
+            if len(pat.elements) > 1:
+                return strip_pattern_name_and_condition(pat.elements[0])
+        # The same kind of get_head_name() check is needed here as well and
+        # is not the same as testing against SymbolPattern.
+        if pat.get_head_name() == "System`Pattern":
+            if len(pat.elements) == 2:
+                return strip_pattern_name_and_condition(pat.elements[1])
+        return pat
+
+    def is_pattern_a_kind_of(pattern: ExpressionPattern, pattern_name: str) -> bool:
+        """
+        Returns `True` if `pattern` or any of its alternates is a
+        pattern with name `pattern_name` and `False` otherwise."""
+
+        if pattern_name == pattern.get_lookup_name():
+            return True
+
+        # Try again after stripping Pattern and Condition wrappers:
+        head = strip_pattern_name_and_condition(pattern.get_head())
+        head_name = head.get_lookup_name()
+        if pattern_name == head_name:
+            return True
+
+        # The head is of the form ``_SymbolName|__SymbolName|___SymbolName``
+        # If name matches with SymbolName, then it is a kind of:
+        if head_name in blanks:
+            if isinstance(head, Symbol):
+                return False
+            sub_elements = head.elements
+            if len(sub_elements) == 1:
+                head_name = head.elements[0].get_name()
+                if head_name == pattern_name:
+                    return True
+        return False
+
+    # If pattern is a Symbol, and coincides with
+    # name, it is an ownvalue:
+
     if pattern.get_name() == name:
         return "own"
-    elif isinstance(pattern, Atom):
+    # If pattern is an ``Atom``, does not have
+    # a position
+    if isinstance(pattern, Atom):
         return None
-    else:
-        head_name = pattern.get_head_name()
-        if head_name == name:
-            return "down"
-        elif head_name == "System`N" and len(pattern.elements) == 2:
+
+    # The pattern is an Expression.
+    head_name = pattern.get_head_name()
+    # If the name is the head name, is a downvalue:
+    if head_name == name:
+        return "down"
+
+    # Handle special cases
+    if head_name == "System`N":
+        if len(pattern.elements) == 2:
             return "n"
-        elif head_name == "System`Condition" and len(pattern.elements) > 0:
-            return get_tag_position(pattern.elements[0], name)
-        elif pattern.get_lookup_name() == name:
-            return "sub"
-        else:
-            for element in pattern.elements:
-                if element.get_lookup_name() == name:
+
+    # The pattern has the form `_SymbolName | __SymbolName | ___SymbolName`
+    # Then it only can be a downvalue
+    if head_name in blanks:
+        elements = pattern.elements
+        if len(elements) == 1:
+            head_name = elements[0].get_name()
+            return "down" if head_name == name else None
+
+    # TODO: Consider process format_values
+
+    if head_name != "":
+        # Check
+        strip_pattern = strip_pattern_name_and_condition(pattern)
+        if strip_pattern is not pattern:
+            return get_tag_position(strip_pattern, name)
+
+    # The head is not a symbol. Is pattern is "name" kind of pattern?
+    if is_pattern_a_kind_of(pattern, name):
+        return "sub"
+
+    # If we are here, pattern is not an Ownvalue, DownValue, SubValue or NValue
+    # Let's check the elements for UpValues
+    for element in pattern.elements:
+        lookup_name = element.get_lookup_name()
+        if lookup_name == name:
+            return "up"
+
+        # Strip Pattern and Condition wrappers and check again
+        if lookup_name in (
+            "System`Condition",
+            "System`Pattern",
+        ):
+            element = strip_pattern_name_and_condition(element)
+            lookup_name = element.get_lookup_name()
+            if lookup_name == name:
+                return "up"
+        # Check if one of the elements is not a "Blank"
+
+        if element.get_head_name() in blanks:
+            sub_elements = element.elements
+            if len(sub_elements) == 1:
+                if sub_elements[0].get_name() == name:
                     return "up"
-        return None
+    # ``pattern`` does not have a tag position in the Definition
+    return None
 
 
 def insert_rule(values, rule) -> None:
@@ -818,7 +931,8 @@ def __init__(
         self.defaultvalues = defaultvalues
         self.builtin = builtin
         for rule in rules:
-            self.add_rule(rule)
+            if not self.add_rule(rule):
+                print(f"{rule.pattern.expr} could not be associated to {self.name}")
 
     def get_values_list(self, pos):
         assert pos.isalpha()
diff --git a/test/core/test_definitions.py b/test/core/test_definitions.py
new file mode 100644
index 000000000..43eb160b0
--- /dev/null
+++ b/test/core/test_definitions.py
@@ -0,0 +1,59 @@
+# -*- coding: utf-8 -*-
+"""
+Tests functions in mathics.core.definition
+"""
+
+import pytest
+
+from mathics.core.definitions import get_tag_position
+from mathics.core.parser import parse_builtin_rule
+
+
+@pytest.mark.parametrize(
+    ("pattern_str", "tag", "position"),
+    [
+        # None
+        ("A", "B", None),
+        ("A_", "B", None),
+        ("A[c_]", "B", None),
+        ("A[3]", "B", None),
+        ("A[B][3]", "B", None),
+        ("A[s[x_]][y]", "s", None),
+        # Ownvalues
+        ("A", "A", "own"),
+        ("A/;A>0", "A", "own"),
+        ("s:(A/;A>0)", "A", "own"),
+        ("(s:A)/;A>0", "A", "own"),
+        ("s:A/;A>0", "A", "own"),
+        # Downvalues
+        ("_A", "A", "down"),
+        ("A[]", "A", "down"),
+        ("_A", "A", "down"),
+        ("A[p_, q]", "A", "down"),
+        ("s:A[p_, q]", "A", "down"),
+        ("A[p_, q]/;q>0", "A", "down"),
+        ("(s:A[p_, q])/;q>0", "A", "down"),
+        # NValues
+        ("N[A[x_], _]", "A", "n"),
+        ("N[A[x_], _]/; x>0", "A", "n"),
+        # Subvalues
+        ("_A[]", "A", "sub"),
+        ("A[x][t]", "A", "sub"),
+        ("(s:A[x])[t]", "A", "sub"),
+        ("(x_A/;u>0)[p]", "A", "sub"),
+        # Upvalues
+        ("S[x_, A]", "A", "up"),
+        ("S[x_, _A]", "A", "up"),
+        ("S[x_, s_A/;s>0]", "A", "up"),
+        ("S[x_, q:A]", "A", "up"),
+        ("S[x_, q:(A[t_]/;t>0)]", "A", "up"),
+        ("A[x_][s[y]]", "s", "up"),
+        ("DisplayForm[boxexpr_InterpretationBox]", "InterpretationBox", "up"),
+        ("ToExpression[boxexpr_InterpretationBox, form___]", "InterpretationBox", "up"),
+        # Just one argument, must be an upvalue
+        ("N[A[s_]]", "A", "up"),
+    ],
+)
+def test_get_tag_position(pattern_str, tag, position):
+    pattern = parse_builtin_rule(pattern_str)
+    assert get_tag_position(pattern, f"System`{tag}") == position