status.i4.v = knob_init_c(scale_factor.r4.v, callback_func.f.v,
				  callback_data.g.v, field_constrain.g.v,

	This routine makes a request to monitor knob changes.

	scale_factor	scale factor to set the sensitivity of the knob
			(a value of 1.0 is standard)
	callback_func	function to be called when the knob is turned
			(called as follows:
			 callback_func(knob_data.s.r, callback_data.g.v)
			 ("knob_data" is a structure of type
	callback_data	data to be passed to "callback_func"
	field_constrain	field constraint information which can be used to
			control when the callback function is called
			(Passing a value of NULL will result in the callback
			function being called whenever the knob is turned.)
			(structure of type WINDOW_FIELD_CONSTRAINT)
	knob_id		returned knob ID (This value can be passed to a
			later call to knob_cancel_c.)

	This function returns ACNET status values as follows:

	OK			success
	CBS_INVARG		invalid scale factor passed
	CBS_MEMFAIL		error in allocating dynamic memory

	This function requires the following include files:

	cbslib_h, acnet_errors_h

	Related functions:

	knob_cancel_c, knob_update_c

	C/C++ usage:

	int	status;
	int	knob_id;
	float	scale_factor = 1.0;
	void	callback_func(KNOB_EVENT_DATA *KNOB_DATA,
			      void *callback_data);
	void	*callback_data = (void *) NULL;
	WINDOW_FIELD_CONSTRAINT	field_constrain = (void *) NULL;

	status = knob_init_c(scale_factor,callback_func,callback_data,