[Coco] Need documentation for 'MOD' pseudo mnemonic

[Willi Kusche]

Hi!

    I've been dis-assembling some of the modules that comprise the
release of OS-9 for the Stellation II Mill 6809 card for the Apple II.
 I was able to assemble an exact match for the "IOMAN" module by using
'FCB' and 'FDB' mnemonics for the module header.  But, after switching
to the 'MOD' mnemonic for the module header, I get two extra bytes in
the binary file generated by the assembler and the checksum at the end
of the module is incorrect.  I'm using the "MAMOU" assembler.

Willi