HP L 5 manual

The command byte identifies two things: 1) the number of replacement (delta) bytes that follow; and 2) where to position the replacement byte string (the left offset). The replacement bytes are some number (up to eight bytes) of consecutive bytes that are used to create the new row from the seed row.

7	5	4	0
Number of bytes to replace (1-8)		Relative offset from last untreated
		byte

If more than eight replacement (delta) bytes are needed, additional command byte/replacement bytes may be added, as shown below:

?*3m#W [(Command Byte)(1 to 8 Replacement

Bytes)][(Command Byte)(1 to 8 Replacement Bytes)]. . .

In the command byte, the upper three bits identify the number of replacement (delta) bytes (which can be 1 to 8 bytes). The lower five bits identify the location the replacement bytes are to be positioned. This position is identified as the offset, or the number of bytes from the treated byte. For example, if there are 5 replacement bytes and the offset is 7, then the replacement bytes replace bytes 7, 8, 9, 10, and 11 (the five bytes beginning at byte 7 from the seed row).

If there is more than one replacement in a row, the second offset is counted from the next untreated byte in the row: the first byte following the last replacement byte.

EN Raster Graphics 6-25