When your printer is NOT an Apple LaserWriter with 68xxx
processor it skips over a bunch of hex data, however it
was done carelessly and CR (or LF) alteration to CRLF
will effectively ruin whole processing. (UNIX lpr ->
VMS Multinet -> Digital PrintServer LPS-20)
Ah yes, in order to implement patches to the firmware of its
printers apple has concocted a number of schemes which use
encryption to "protect" the patch content, thus there were
large blocks of hex in the prelude (always named md BTW).
Unfortunatly it was awkward to ensure that the hex code would
be consumed under both clauses of a conditional, and apple has
implemented several different schemes to deal with that, one of
which involved knowing how many characters were in the hex field.
Obviously any postprocessor which makes that knowledge false
(by adding or removing CR or LF) causes trouble.
I havent had reason to examine the present schemes (LW 7.1.x, LW 8.x),
but I beleive they are more robust, still there is a large
installed base of users who are using the older troublesome
technology that shipped with system 6.
--
dnaa s emery <de19(_at_)Umail(_dot_)umd(_dot_)edu>