HP 4 FAMILY - Manual (Page 130)

Media Source
Command
The Paper (Media) Source command (?&l#H) for the
DeskJet 1600C uses a value of 5 for its optional sheet
feeder and also supports a value of 7 (autoselect). A value of
7 selects the current printer default source. The user,
through the application, may select a particular tray for the
first page or pages (for example, a fancy cover page), then
choose autoselect to pull paper from a default tray (for
example, containing standard paper). This is different than
option 0, which continues printing from the currently
selected source. The "default" source may be user-selected,
or based upon the printer’s own algorithm.
Compression Method
Command
The Compression Method command (?*b#M) for
the DeskJet 1600C supports Method 9 compression
(compressed replacement delta row encoding) in addition
to compression methods 0, 1, 2, 3, and 5.
Method 9 (Replacement Delta Row Encoding)
Like Method 3, this method replaces only bytes in the
current row that differ from the preceding (seed) row.
Unlike Method 3, the replacement (delta) bytes may be
encoded.
The replacement byte string (delta compression string)
consists of a command byte, optional offset bytes, optional
replacement count bytes, and the replacement data.
Command
Byte
Optional Offset Bytes Optional Replacement Count Bytes Data
Bytes
2-94 Printer-Specific Differences