>> What I got back was apparently telling me that QR-Codes do >> offer 45 different characters, so hence base-45. This is, of >> course, equivalent to saying that ASCII offers 95 graphic >> characters, so with that argument base-64 should have been >> base-95 all along. > > That ASCII example is interesting because the Base-64 design, > IIR, carefully considered and eliminated characters that were > not in ISO 646-BV and then settled on upper and lower case > letters and the digits and then, to get to 64, added "+" and "/" > (and "=" for padding). Almost any of the other 30 graphics > would have raised issues. Which is exactly what not has been done for base45 — this just uses the entire character set offered by QR-Codes in character mode. >> Instead of trying to fix this document, another specification >> could be written that defines a base-41 (or base-40 + >> overflow) variant that could present fewer of the >> interoperability concerns base-45 does. > > Well... One can probably make a case for almost any encoding of > this general type. Well, this happened for base64, which was revisited for in-URL usage, and yielded base64url. I’m essentially asking for a base45url, except that this is easier to do with a base41/base40-with-overflow approach. > every > new ASCII-compatible encoding we introduce is a new problem for > universal interoperability, a problem that gets more serious if > one cannot easily tell them apart by simple examination of the > strings. What we’d probably do for the base41/40 encoding is describe in more detail how that is embedded in various environments. Triggering use case could be the URI generated from a standard smartphone camera QR-Code reader (base45 is used with “HC0” for EDGC, but that isn’t even registered, maybe because the URI mapping is broken with % and space in the character set). But again, I’m writing this because I believe this base45 should be published despite its flaws (so I can refer to it as “legacy base45” later… :-). Grüße, Carsten -- last-call mailing list last-call@xxxxxxxx https://www.ietf.org/mailman/listinfo/last-call
