status.i4.v = is_valid_data_event_string_c(string.i1a.r

	This routine determines whether or not a string is a valid
	data event string.

	string		data event string to test
			(up to DATA_EVENT_MAX_LEN characters)
	[length]	length of string to test
			(default is 0 which results in the routine
			 determining the length of the string)
	[allow_extended] flag indicating whether or not allow extended
			 data event strings
			 (TRUE -> allow extended data event strings
				  (Note: Extended data events are currently
				   only supported by higher level software,
				   not by front ends.),
			  FALSE -> don't allow extended data event strings

	This function returns ACNET status values as follows:

	TRUE			valid data event string
	FALSE			not a valid data event string

	This function requires the following include files:

	cbslib_h, acnet_errors_h

	Related functions:

	is_default_data_event_string_c, is_oneshot_data_event_string,
	is_periodic_data_event_string_c, is_clock_event_data_event_string_c,
	is_state_data_event_string_c, data_event_string_to_type_c,
	string_to_data_event, data_event_to_string,
	build_oneshot_data_event_data, numeric_to_ascii(_c),
	ascii_to_numeric(_c), data_event_string_to_ftd, data_event_to_ftd,
	ftd_to_data_event_c, ftd_to_data_event_string_c, clib_sprintf,

	C/C++ usage:

	static const char	string[] = "s,v:alive,0,100,*";
	int	status;
	int	length = 0;
	int	allow_extended = FALSE;

	status = is_valid_data_event_string_c(string,length,allow_extended);