DEFUN ("define-prefix-command", Fdefine_prefix_command, Sdefine_prefix_command, 1, 3, 0,
doc: /* Define COMMAND as a prefix command. COMMAND should be a symbol.
-A new sparse keymap is stored as COMMAND's function definition and its value.
-If a second optional argument MAPVAR is given, the map is stored as
-its value instead of as COMMAND's value; but COMMAND is still defined
-as a function.
+A new sparse keymap is stored as COMMAND's function definition and its
+value.
+This prepares COMMAND for use as a prefix key's binding.
+If a second optional argument MAPVAR is given, it should be a symbol.
+The map is then stored as MAPVAR's value instead of as COMMAND's
+value; but COMMAND is still defined as a function.
The third optional argument NAME, if given, supplies a menu name
string for the map. This is required to use the keymap as a menu.
This function returns COMMAND. */)