All routines that perform I/O assume that output files have already been opened.
When extra output is desired it is often for debugging, so since output is often buffered and only written in chunks, a system-dependent routine, JT_ FLUSHUNIT, is called after debug information is written. This way if the code dies, information that has recently been ``written'' out will not be lost, which is important since this is often the most important in tracking down the problem.