NAME
	  glDepthMask -	enable or disable writing into the depth
	  buffer


     C SPECIFICATION
	  void glDepthMask( GLboolean flag )


     PARAMETERS
	  flag	Specifies whether the depth buffer is enabled for
		writing.  If flag is GL_FALSE, depth buffer writing is
		disabled.  Otherwise, it is enabled.  Initially, depth
		buffer writing is enabled.

     DESCRIPTION
	  glDepthMask specifies	whether	the depth buffer is enabled
	  for writing.	If flag	is GL_FALSE, depth buffer writing is
	  disabled.  Otherwise,	it is enabled.	Initially, depth
	  buffer writing is enabled.

     ERRORS
	  GL_INVALID_OPERATION is generated if glDepthMask is executed
	  between the execution	of glBegin and the corresponding
	  execution of glEnd.

     ASSOCIATED	GETS
	  glGet	with argument GL_DEPTH_WRITEMASK

     SEE ALSO
	  glColorMask, glDepthFunc, glDepthRange, glIndexMask,
	  glStencilMask