This routine unlocks any locked records held by the current process in the passed file. It is not an error to call this routine when there are no locked records. This routine does not affect the current file position or key of reference. This routine will not unlock any records if it is called during a transaction. "Commit" (see below) should be used instead. The "unlock" routine has only one parameter, f. F must be a valid file handle returned by OPEN.