status.i4.v = snpplt(function_type.i2.r, top_row.i2.r, left_column.i2.r
			     [,diag_flags.i2.r] [,options.u4.r])
	status.i4.v = snpplt_c(function_type.i2.v, top_row.i2.v, left_column.i2.v
			       [,diag_flags.i2.v] [,options.u4.v])

	This routine is used by PA's to interface to the Snapshot Plot
	package.  There are two ways that a PA can call the SNP interface.
	The normal method requires that the PA devote an area 3 rows by 60
	columns on the color TV to SNP.  The second method requires only 5
	columns on one row of the color TV.  This interrupt field is used to
	create a window containing the SNP interface.  (Note:  The row and
	column arguments are only valid for SNP_INIT, SNP_WIN_INIT,
	and SNP_INIT_WBORDER modes.)

	function_type	function code
			(SNP_INIT -> initialize normal snapshot plot interface
				     with upper left corner at
				     (top_row, left_column),
			 SNP_TERM -> terminate SNP plot interface,
			 SNP_INTERRUPT -> keyboard interrupt for normal
			 SNP_WIN_INIT -> initialize "SNP in a window" at
					 (top_row, left_column) with "*SNP*"
					  written at (top_row, left_column),
			 SNP_WIN_CALLBACK_INIT -> initialize "SNP in a window"
						  at (top_row, left_column)
						  with "*SNP*" written at
						  (top_row, left_column) and
						  handled by a callback
						  (requires the use of
			 SNP_WIN_INTERRUPT -> keyboard interrupt for "SNP in
					      a window".  SNPPLT will display
					      the SNP window, process user
					      keyboard interrupts within the
					      window, delete the window, and
					      then return to the caller,
			 SNP_INIT_SDA -> initialize special SNP interface for
					 plotting snapshots from SDA files with
					 upper left corner at (top_row,
			 SNP_CREATE_WIN	-> create callable snapshot plot window,
			 SNP_REPOSITION -> reposition normal SNP plot interface
					   at (top_row, left_column),
			 SNP_DELETE -> delete normal SNP plot interface,
			 SNP_INIT_WBORDER -> same as SNP_INIT except that a
					     a visible border surrounds the
					     plot interface,
			 SNP_START_PLOT -> erase screen and start plot,
			 SNP_START_PLOT_NOERASE -> start plot without erase)
	top_row		top row of snapshot plot interface
	left_column	leftmost column of snapshot plot interface
	[diag_flags]	diagnostics flags (default is 0)
	[options]	display options
			(FTP_OPT_NONE -> no options selected (default),
			 FTP_OPT_NO_DEVICE_COMPLETE -> suppress device

	This function returns status values as follows:

	OK			success
	CLIB_NOINIT		snapshot plot interface does not exist
	otherwise		window ID for SNP_INIT or SNP_INIT_WBORDER

	This function requires the following include files:

	clib_h, acnet_errors_h

	Related functions:

	snp_setup, snp_start, snp_file_menu_c, snp_start_plot_c,
	snp_start_plot_from_file_c, snp_read_plot_setup_file_c,
	snp_export_data, snp_set_sda_info_c, fstplt, ftp_setup, ftp_start,
	ftp_file_menu_c, ftp_start_plot_c, ftp_start_plot_from_file_c,
	ftp_read_plot_setup_file_c, ftp_calculated_trace_c,
	window_field_create_c, window_intype

	C/C++ usage:

	short	function_type = SNP_INIT;
	short	top_row;
	short	left_column = 1;
	short	diag_flags = 0;
	int	status;
	unsigned int	options = SNP_OPT_NONE;

	status = snpplt(&function_type,&top_row,&left_column,&diag_flags,
	status = snpplt_c(function_type,top_row,left_column,diag_flags,