1 files changed, 61 insertions, 27 deletions
diff --git a/Help/command/function.rst b/Help/command/function.rst
index 7ffdfee65..53ba75481 100644
--- a/Help/command/function.rst
+++ b/Help/command/function.rst
@@ -1,36 +1,70 @@
 function
 --------
 
-Start recording a function for later invocation as a command::
-
-  function(<name> [arg1 [arg2 [arg3 ...]]])
-    COMMAND1(ARGS ...)
-    COMMAND2(ARGS ...)
-    ...
-  endfunction(<name>)
-
-Define a function named ``<name>`` that takes arguments named ``arg1``,
-``arg2``, ``arg3``, (...).
-Commands listed after function, but before the matching
-:command:`endfunction()`, are not invoked until the function is invoked.
-When it is invoked, the commands recorded in the function 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.
-Additionally ``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.
+Start recording a function for later invocation as a command.
+
+.. code-block:: cmake
+
+  function(<name> [<arg1> ...])
+    <commands>
+  endfunction()
+
+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
+argument of the opening ``function`` command.
 
 A function opens a new scope: see :command:`set(var PARENT_SCOPE)` for
 details.
 
 See the :command:`cmake_policy()` command documentation for the behavior
 of policies inside functions.
+
+See the :command:`macro()` command documentation for differences
+between CMake functions and macros.
+
+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.