SCS printing issues

Around 4:00 yesterday, I managed to get the first stage of my printing
project to generate a spool file, entirely by feeding an SCS data stream
into the appropriate APIs, and get it to print to a LaserJet hooked up
to my 3487, with the 3487's printer emulator set to emulate a 3812.
Within an hour, I was printing test pages that showed selected words in
bold face type. 'Twould seem the first battle is won (but it could be a
very long war, with lots of casualties, particularly my wits).

Would anybody happen to know why the first 15 bytes of the print data
space show up (if printable) when displaying the spool file on the
screen, but disappear when printed? I've already determined that if I
pack those first 15 bytes with nulls, the spool file both displays and
prints correctly, but I still wonder what becomes of them.

And would anybody happen to know where I might find information on SCS
control codes, beyond what's in the 5250 book, what's in the "Guide to
Programming for Printing," and what's in the JTOpen source for the
various Java Toolbox SCS writer classes? As my previous query might
suggest, I'm particularly interested in the DCA-FFT extensions, used
when OfficeVision prints to a 3812-SCS.

--
James H. H. Lampert
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