writem(3G)

NAME
     writem - grants write permission to bitplanes

FORTRAN 77 SPECIFICATION
     subroutine writem(wtm)
     integer*4 wtm

PARAMETERS
     wtm   expects a mask whose bits control which bitplanes are available for
           drawing and which are read only.

           The mask contains one bit per available bitplane. If a bit is set
           in the writemask, the system writes the current color index into
           the corresponding bitplane. If a bit is set to zero in the
           writemask, the corresponding bitplane is read-only.

DESCRIPTION
     Use writem to reserve bitplanes for special purposes.  When the writemask
     marks a bitplane as read-only, that bitplane is write protected from
     ordinary drawing routines.

     Use RGBwri in RGB mode.

SEE ALSO
     color, drawmo, RGBwri

BUGS
     writem does not work properly on the IRIS-4D VGX, VGXT and SKYWRITER
     models when the current drawmode is not NORMDR.