I really did hate to rename the files, but when I was creating the Master Catalog Index filenames were all over the place
for the 1st 180 sets. I'm a stickler for not changing filenames myself since it can help to discover duplicates if you just
use windows filecopy, but I made an exception in this case. Also if you create just a simple file listing everything appears
in numerical order - it simply made things much easier to work with.