Help: Document that function invocation is case-insensitive

Help/command/function.rst

@@ -9,27 +9,9 @@ Start recording a function for later invocation as a command.
     <commands>
   endfunction()
 
-Defines a function named ``<name>`` that takes arguments
-named ``<arg1>``, ...
-The ``<commands>`` in the function definition are recorded;
-they are not invoked until the function is invoked. When
-the function is invoked, the recorded ``<commands>`` are first
-modified by replacing formal parameters (``${arg1}``, ...)
-with the arguments passed, and then invoked as normal commands.
-
-In addition to referencing the formal parameters you can reference the
-``ARGC`` variable which will be set to the number of arguments passed
-into the function as well as ``ARGV0``, ``ARGV1``, ``ARGV2``, ...  which
-will have the actual values of the arguments passed in.
-This facilitates creating functions with optional arguments.
-
-Furthermore, ``ARGV`` holds the list of all arguments given to the
-function and ``ARGN`` holds the list of arguments past the last expected
-argument.
-Referencing to ``ARGV#`` arguments beyond ``ARGC`` have undefined
-behavior. Checking that ``ARGC`` is greater than ``#`` is the only way
-to ensure that ``ARGV#`` was passed to the function as an extra
-argument.
+Defines a function named ``<name>`` that takes arguments named
+``<arg1>``, ...  The ``<commands>`` in the function definition
+are recorded; they are not executed until the function is invoked.
 
 Per legacy, the :command:`endfunction` command admits an optional
 ``<name>`` argument. If used, it must be a verbatim repeat of the
@@ -40,3 +22,46 @@ details.
 
 See the :command:`cmake_policy()` command documentation for the behavior
 of policies inside functions.
+
+Invocation
+^^^^^^^^^^
+
+The function invocation is case-insensitive. A function defined as
+
+.. code-block:: cmake
+
+  function(foo)
+    <commands>
+  endfunction()
+
+can be invoked through any of
+
+.. code-block:: cmake
+
+  foo()
+  Foo()
+  FOO()
+
+and so on. However, it is strongly recommended to stay with the
+case chosen in the function definition. Typically functions use
+all-lowercase names.
+
+Arguments
+^^^^^^^^^
+
+When the function is invoked, the recorded ``<commands>`` are first
+modified by replacing formal parameters (``${arg1}``, ...) with the
+arguments passed, and then invoked as normal commands.
+
+In addition to referencing the formal parameters you can reference the
+``ARGC`` variable which will be set to the number of arguments passed
+into the function as well as ``ARGV0``, ``ARGV1``, ``ARGV2``, ...  which
+will have the actual values of the arguments passed in.  This facilitates
+creating functions with optional arguments.
+
+Furthermore, ``ARGV`` holds the list of all arguments given to the
+function and ``ARGN`` holds the list of arguments past the last expected
+argument.  Referencing to ``ARGV#`` arguments beyond ``ARGC`` have
+undefined behavior.  Checking that ``ARGC`` is greater than ``#`` is
+the only way to ensure that ``ARGV#`` was passed to the function as an
+extra argument.