in @code{"u=rwx"}, the function converts it to the equivalent numeric
value using @code{file-modes-symbolic-to-number} and returns the
result. If the specification is relative, as in @code{"o+g"}, then
-the permissions on which the specification is based is taken from the
+the permissions on which the specification is based are taken from the
mode bits of @var{base-file}. If @var{base-file} is omitted or
@code{nil}, the function uses @code{0} as the base mode bits. The
complete and relative specifications can be combined, as in