Things that make me go "hmm".

[lederhosen]

Finding a way to store an important extra byte of data in a fixed-length unit identifier: good.

Achieving this by overwriting the checksum digit: probably not so good.

Combining this with a system that recalculates the checksum when you edit one of the other digits: probably less good again.

Comments

[torin3.livejournal.com]

Great Googly-Moogly!!

[tenner.livejournal.com]

Heh... oops.

[nefaria.livejournal.com]

Reminds me of the fun times I had converting mm-dd-yy string dates into yyyymmdd long integers for Y2K. I never understood why they'd want to store important data in an ambiguous 2-digit year format.