This article is from the CD-Recordable FAQ, by Andy McFadden (email@example.com) with numerous contributions by others.
The ISO-9660 standard says the version number (a semicolon followed by a
number at the end of every filename) has to be there. Most operating
systems simply ignore it, but until recently the Mac didn't, causing some
(For the Mac, look at "ISO 9660 File Access" in the System:Extensions
folder with Command-I. If the version shown is 5.0 or greater, your system
should handle the version numbers just fine. If not, you should update
your system software.)
If you can't find a way to work around it, "mkisofs" has an option to omit
the version number when constructing an ISO-9660 image.