It's certainly true that it has a nasty growth curve (exponential in version number; probably worse in number of active terms). I just think it's fun for low v

It's certainly true that it has a nasty growth curve (exponential in version number; probably worse in number of active terms). I just think it's fun for low value things, and interesting if you're in the situation you have a huge feature set relative to the number of active features, since it incurs no penalty for fields that are 0. Any time you have about ~1% features being present, it can make a difference. Example: if you have about 5 of 500 fields with 16 possible values represented, storing all the 0s is expensive. Using a naive 4-bits-per-field, you end up with 2000 bits, whereas, using my method, you only use ~620. Even using a 500bit number to flag which fields are present and then listing just those fields in order only saves you about ~100 bits over my method. Plus, I manage to spark off a discussion about math and the problem, rather than just whining about it being hard, which I consider to be a good thing.