Yeah, I confused myself. Point withdrawn.
@Minh_Nguyen pointed to some examples, though honestly, the need for ordered lists is probably so low that no standard has been established. The only two use cases where order matters (and that I know of) are lane tagging and opening_hours syntax; the latter being so complex and custom that I wouldn’t use it as an OSM convention.
I probably overstated the usage of | since to my recollection those uses are all in some way related to lanes. Though I’ve tried to get it used in the context of phone numbers.
Whichever gets chosen, it’s probably safe to document that the order matters, even if it might be obvious.
Most map renderers should just ignore it, I agree. It’s just something of interest when actually wanting to map what exists on the ground.
Not quite the answer I want, so I ask more directly: Is there a law or statute that prescribes the ordering of names on street signage? One example suffices, ideally in english, otherwise please translate the relevant excerpt. I certainly wasn’t able to find one for the canton of Bern, but I’ve been wrong before.
Originally, I was going for a sort of “If there is no law, then it doesn’t belong on an administrative boundary”, but then I wondered about the national speed limits in Germany, since those aren’t mapped there either despite being law. And I found the StVO relation. It’s of type defaults, which then applies to the area of Germany. Maybe that would be a better approach. Also allows for reuse in case the same law applies to different regions (I’m thinking of the gaeltacht areas discussed here).
What to do if there is no law? I’d say only tag the object it applies to, though it can be difficult to discern if it’s a convention among all street signage.