* doc/lispref/sequences.texi (Char-Tables): Clarify that extra
slot numbers are zero-based. (Bug#21467)
@end defun
@defun char-table-extra-slot char-table n
-This function returns the contents of extra slot @var{n} of
-@var{char-table}. The number of extra slots in a char-table is
+This function returns the contents of extra slot @var{n} (zero based)
+of @var{char-table}. The number of extra slots in a char-table is
determined by its subtype.
@end defun
@defun set-char-table-extra-slot char-table n value
-This function stores @var{value} in extra slot @var{n} of
+This function stores @var{value} in extra slot @var{n} (zero based) of
@var{char-table}.
@end defun