Checksum doesn't change when data moved around in a file.

[NotDomo]

I had to correct my carddata.txt by switching around some data in some of the columns, and the checksum stayed the same.

I can get around this by using uninstall.txt, but some plugin creators might not notice when they're fixing similar bugs.

[ani-mayhem]

"... it is literally a sum of the data."

http://www.lackeyccg.com/forum/index.php?topic=808.0

[NotDomo]

Oh, that's... interesting? Good to know, thanks. =)

Edit: Made a bad assumption in my comment here. Backwards compatibility does matter, 'cause checksums are generated on the fly when checking online update.
I hope there's some version in the future where you just say frack it and opt for the unique checksum. The earlier, the easier it will be on all the plugins. XD One could always just compare with old updatelist file, or compare with both checksums.