- "Return the documentation string of Doc-Type for X, or NIL if
- none exists. System doc-types are VARIABLE, FUNCTION, STRUCTURE, TYPE,
- SETF, and T.")
+ "Return the documentation string of Doc-Type for X, or NIL if none
+exists. System doc-types are VARIABLE, FUNCTION, STRUCTURE, TYPE, SETF, and T.
+
+Function documentation is stored separately for function names and objects:
+DEFUN, LAMBDA, &co create function objects with the specified documentation
+strings.
+
+ \(SETF (DOCUMENTATION NAME 'FUNCTION) STRING)
+
+sets the documentation string stored under the specified name, and
+
+ \(SETF (DOCUMENTATION FUNC T) STRING)
+
+sets the documentation string stored in the function object.
+
+ \(DOCUMENTATION NAME 'FUNCTION)
+
+returns the documentation stored under the function name if any, and
+falls back on the documentation in the function object if necessary.")