status.i4.v = bpm_next_unlinked_file_c(file_number.i4.v, next_file.i4.r)

	This routine searches through a master BPM file for the next one
	that is not linked to another file, unprotected, and not a reference
	file.  See bpm_machine_c.

	file_number	number of file to start search (starts at 1)
	next_file	next available file number (starts at 1)

	This function returns ACNET status values as follows:

	OK			success
	CBS_INVARG		invalid file number passed
	CBS_NO_SUCH		no available file exists
	SQL_xxx			database error

	This function requires the following include files:

	ul_cbsaux/bpmuti.h, acnet_errors_h

	Related functions:

	bpm_machine_c, bpm_file_link_info_c, bpm_link_file_c,
	bpm_unlink_file_c, bpm_find_oldest_file_number_c, bpm_get_save_file,
	bpm_get_default_save_file, bpm_set_save_file, bpm_save_data,
	bpm_file_menu_c, bpm_directory_info

	C/C++ usage:

	int	status;
	int	file_number = 1;
	int	next_file;

	status = bpm_next_unlinked_file_c(file_number,&next_file);