Thanks to tr for this link http://lists.debian.org/debian-knopp.../msg00009.html . A doubled block size is now being used in the statement for compressing the KNOPPIX file for Knoppix 5.1 (131072 instead of 65536).
A note is output by the genisoimage (new fork of mkisofs) concerning the new syntax :-
Code:
Warning, number as file string found. Assuming old command syntax and choosing compatible parameters (-m -B 131072). See the usage info (-h) for better/correct parameters.