[Tagging] Opening hours syntax for non Gregorian calendar

[Rory McCann]

On 22/05/2019 14:31, Paul Allen wrote:
> The problem with that is the same problem as allowing every language
> on the planet to use their own abbreviations for month names.  Only
> worse.

I'm not proposing that, I suggest we create a (short) list of accepted
calendar systems, and accepted abbreviations for each month in that
calendar. We don't have to expand it to all languages (you're right, it
would very impractical).

"Show in other languages" doesn't solve the problem of the months not
matching up.

> Is this a real problem?  MARchesvan in the Judaic calendar is a 
> collision with MARch, so we'd have to switch to 6-letter 
> abbreviations.  The Islamic calendar has Rabi-Al-Awwal and 
> Rabi-Al-Thani; Jumada-Al-Awwal and Jumada-Al-Thani; Zul-Qaadah and 
> Zul-Hijjah, so that would need some though (are RAA, RAT, JAA, JAT, 
> ZUQ ZUH acceptable?).

I'd leave it up to people familiar with the area to come up with good
abbreviations. I'm sure they already have recognizable abbreviations.

`opening_hours` is machine readable, but it's also (mostly) human
readable. If you put islamic/etc months in it, and a tool doesn't
support that, it can just display the raw tag text to the user who will
probably be able to read it and know what the opening hours are! By
putting data in `opening_hours` (not `opening_hours:islamic`) and using
local appropriate names, we retain that benefit. It degrades gracefully.