NAME
	  fglIndexMask - control the writing of	individual bits	in the
	  color	index buffers


     FORTRAN SPECIFICATION
	  SUBROUTINE fglIndexMask( INTEGER*4 mask )


     PARAMETERS
	  mask	Specifies a bit	mask to	enable and disable the writing
		of individual bits in the color	index buffers.
		Initially, the mask is all 1's.

     DESCRIPTION
	  fglIndexMask controls	the writing of individual bits in the
	  color	index buffers.	The least significant n	bits of	mask,
	  where	n is the number	of bits	in a color index buffer,
	  specify a mask.  Where a 1 (one) appears in the mask,	it's
	  possible to write to the corresponding bit in	the color
	  index	buffer (or buffers). Where a 0 (zero) appears, the
	  corresponding	bit is write-protected.

	  This mask is used only in color index	mode, and it affects
	  only the buffers currently selected for writing (see
	  fglDrawBuffer).  Initially, all bits are enabled for
	  writing.

     ERRORS
	  GL_INVALID_OPERATION is generated if fglIndexMask is
	  executed between the execution of fglBegin and the
	  corresponding	execution of fglEnd.

     ASSOCIATED	GETS
	  fglGet with argument GL_INDEX_WRITEMASK

     SEE ALSO
	  fglColorMask,	fglDepthMask, fglDrawBuffer, fglIndex,
	  fglIndexPointer, fglStencilMask