3 files changed, 22 insertions, 1 deletions
diff --git a/language/functions.rst b/language/functions.rst
new file mode 100644
index 0000000..86d1144
--- /dev/null
+++ b/language/functions.rst
@@ -0,0 +1,20 @@
+Functions
+---------
+
+.. crowbar:element:: FunctionDeclaration <- FunctionSignature ';'
+
+    A function declaration defines the return type, name, and arguments of a function without specifying its behavior.
+    It is generally used as part of an API boundary.
+
+.. crowbar:element:: FunctionDefinition <- FunctionSignature Block
+
+    A function definition provides the actual behavior of a function, which may have been declared previously or may not.
+
+    .. todo::
+
+        define function linkage/exportedness
+
+.. crowbar:element:: FunctionSignature <- Type identifier '(' SignatureArguments? ')'
+                     SignatureArguments <- Type identifier (',' Type identifier)* ','?
+    
+    A function signature specifies the return type, name, and arguments of a function.
diff --git a/language/index.rst b/language/index.rst
index eb2d92c..66492a9 100644
--- a/language/index.rst
+++ b/language/index.rst
@@ -18,3 +18,4 @@ Syntax elements in this document are given in the form of `parsing expression gr
     source-file
     include
     type-definition
+    functions
diff --git a/language/scanning.rst b/language/scanning.rst
index c45e6b8..3ed9bfe 100644
--- a/language/scanning.rst
+++ b/language/scanning.rst
@@ -14,7 +14,7 @@ Scanning
         One of the literal words ``bool``, ``break``, ``case``,
         ``char``, ``const``, ``continue``, ``default``, ``do``, ``double``,
         ``else``, ``enum``, ``extern``, ``float``, ``for``, ``fragile``,
-        ``function``, ``if``, :crowbar:ref:`include <IncludeStatement>`, ``int``, ``long``, ``return``,
+        ``function``, ``if``, :crowbar:ref:`include <IncludeStatement>`, ``int``, ``long``, ``opaque``, ``return``,
         ``short``, ``signed``, ``sizeof``, ``struct``, ``switch``, ``union``,
         ``unsigned``, ``void``, or ``while``.