nroff driver table info wanted

[martello at cadre.UUCP]

I am in the process of hacking together a new driver table to go
in /usr/lib/term for nroff and ran into a few questions that
can only be answered by hacking through the sources (i think).
 - what is the first byte for in each codetab entry? my interpretation
   of all bytes after the first is the actual sequence to send, but what 
   is the first one for?
 - can anyone shed some light on essentially all the variables at the
   top of the table in the structure.  some of their names are
   obvious (like plot on and bold on), some are not so obvious
   (like twinit) and some are confusing (what units are the horizontal
   and vertical increments in, etc.--it would not appear standard since
   all printers have INCH defined the same).
any help is appreciated.  thanks.
al martello
UUCP: { akgua | allegra | cmcl2 | cmucsg  | cmucspt | 
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