In the 2010s I had a startup generating a bunch of QR Codes. We generated URLs with a BASE32 variant plus upper case domain and scheme so we could stay within the 5.5 bits per character encoding. I kept trying to explain this feature to people, but it was an uphill battle. To this day I still use upper case w/ URLs JUST-IN-CASE I want to put them in a QR Code.
One minor annoyance I have is the ``git`` command line tools (at least the ones distributed w/ Debian) are case sensitive w/ URLs, so if you try the command:
git clone HTTPS://GIT.BI6.US/TQT
git clone https://GIT.BI6.US/TQT
I should probably publish the BASE32 variant we used. Mostly just removed the I's O's and a few other letters that could easily be confused with digits or with other letters.
Interesting, that means git is violating the URI spec. Quoting RFC 3986:
> [...] schemes are case-insensitive [...] An implementation should accept uppercase letters as equivalent to lowercase in scheme names (e.g., allow "HTTP" as well as "http") [...]
https://datatracker.ietf.org/doc/html/rfc3986#section-3.1
`https://GIT.BI6.US/TGT` is actually not that bad because the optimal encoding will use the 8-bit encoding only for the `https` part and you only need 13 more alphanumeric characters to beat the full 8-bit encoding (if my calculation is correct).
Can you mix encodings in a QR code?
yes.