NAME
	  fglPassThrough - place a marker in the feedback buffer


     FORTRAN SPECIFICATION
	  SUBROUTINE fglPassThrough( REAL*4 token )


     PARAMETERS
	  token	 Specifies a marker value to be	placed in the feedback
		 buffer	following a GL_PASS_THROUGH_TOKEN.

     DESCRIPTION
	  Feedback is a	GL render mode.	 The mode is selected by
	  calling fglRenderMode	with GL_FEEDBACK.  When	the GL is in
	  feedback mode, no pixels are produced	by rasterization.
	  Instead, information about primitives	that would have	been
	  rasterized is	fed back to the	application using the GL.  See
	  the fglFeedbackBuffer	reference page for a description of
	  the feedback buffer and the values in	it.

	  fglPassThrough inserts a user-defined	marker in the feedback
	  buffer when it is executed in	feedback mode. token is
	  returned as if it were a primitive; it is indicated with its
	  own unique identifying value:	 GL_PASS_THROUGH_TOKEN.	 The
	  order	of fglPassThrough commands with	respect	to the
	  specification	of graphics primitives is maintained.

     NOTES
	  fglPassThrough is ignored if the GL is not in	feedback mode.

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

     ASSOCIATED	GETS
	  fglGet with argument GL_RENDER_MODE

     SEE ALSO
	  fglFeedbackBuffer, fglRenderMode