+\paragraph*{Semantics}
+An identifier is a sequence of nondigit characters (including the underscore \_, the lower
+case and upper case Latin letters, and other characters) and digits, which designates one
+or more items. Lowercase and uppercase letters are distinct. There is a specific limit of
+65535 characters for an identifier.
+\linebreak
+
+When preprocessing tokens are converted to tokens during translation step six, if a
+preprocessing token could not be converted to either a keyword or an identifier, it is
+converted to a keyword.
+
+\paragraph*{Predefined identifiers}
+Any identifiers that begin with the prefix \_\_builtin, or are within the reserved name
+space are reserved by the implementation.