<B>link</B>) and <I>bitmap</I> is a bitmap
to display for the operation.
<BR>If <I>bitmap</I> is empty, the default bitmap of the base operation is used for the
sub operation.
<BR><I>subop</I> can be a base operation, in order to change the bitmap of a base operation.
In this case, <I>baseop</I> must be empty or equal to <I>subop</I>.
<BR><I>mod</I> is the modifer key for the operation. It can be:
<UL>
<LI><B>none</B> to specify that no modifier key is pressed. This modifier can only be used
with a sub oper