`opening_hours` on even/odd days

I’ve noticed some strange syntax that is not recognised by OsmAnd and by the evaluation tool on Node: ‪Д-р Дарина Наумова‬ (‪4978230146‬) | OpenStreetMap @ version 3. I’ve looked up on the wiki and there is a similar thing there.

week 1-53/2 Fr 09:00-12:00; week 2-52/2 We 09:00-12:00
Open from 09:00 to 12:00 on Fridays of odd weeks and on the Wednesdays of even weeks

That dentist (and many other doctors in Bulgaria) works in the afternoon on even days and in the morning on odd days (or vice-versa). I’ve tried to follow the same syntax but using day instead of week. OsmAnd didn’t pick it up (but it also didn’t pick up the one with even/odd weeks). The evaluation tool also doesn’t like it.

There is an issue on Github about it (Open with periodicity "n" within a range of consecutive monthdays · Issue #252 · opening-hours/opening_hours.js · GitHub) but as far as I can see, it hasn’t moved much.

My question is whether this is a valid way to mark these opening hours? Is there another way to do it, that’s not documented?

It’s not “valid” “yet”, as it is an unspecified / unprescribed extension. Using comments is the best fallback. Street parking - OpenStreetMap Wiki