returns @code{fill-prefix}.
In general, @code{read-variable} is similar to @code{read-command},
-but uses the predicate @code{user-variable-p} instead of
+but uses the predicate @code{custom-variable-p} instead of
@code{commandp}:
-@cindex @code{user-variable-p} example
+@cindex @code{custom-variable-p} example
@example
@group
(read-variable @var{prompt})
@equiv{}
(intern
(completing-read @var{prompt} obarray
- 'user-variable-p t nil))
+ 'custom-variable-p t nil))
@end group
@end example
@end defun