file_id	IN:	Access identifier returned by Hstartread or Hnextread
	tag	IN:	Tag to be identified with the returned reference number

	Purpose	Returns a reference number that is unique for the specified file that will correspond to the specified tag. Creates a new tag/reference number pair.
	Return value	Returns the reference number if successful and 0 otherwise.
	Description	Successive calls to Hnewref will generate a increasing sequence of reference number values until the highest possible reference number value has been returned. It will then return unused reference number values starting from 1 in increasing order.