Hmm, I found this and it is indeed different..
from http://www.tek-tips.com/viewthread.cfm?qid=1577259&page=1 user guptadeepak03
Actually I did some research on that too. I found it hard way that there are few differences in the way the formats are in PCL-XL and PCL-5. To quote from the reference manual provided by HP(PCL-XL ver 2.1):
The PCL XL implementation follows the
PCL5 implementation except in the
following:
1) the seed row is
initialized to zeroes and contains the
number of bytes defined by SourceWidth
in the BeginImage operator.
2) the delta row is preceded by a 2-byte byte
count which indicates the number of
bytes to follow for the delta row. The
byte count is expected to be in LSB
MSB order.
3) to repeat the last row, use the 2-byte byte count of 00 00.
Will mark this answered as soon as I can.. Thanks..