HP L5 manual Control BIT =

count. If the replacement count byte is 255, another replacement count byte follows. The last replacement count byte is indicated by a value less than 255. One more than the total replacement byte count will be replaced.

CONTROL BIT = 1

7	6	5	4	0
Control Bit = 1		Offset Count	Replacement Count

If the control bit is 1, the replacement data is run length encoded. the bit boundaries are different than if the control bit is 0: bits 5-6 contain the offset count, and bits 0-4 contain the replacement count. As when the control bit is 0, optional offset bytes and replacement bytes may be added.

2-96 Printer-Specific Differences