Correct procedure for tagging semaphore Railway signals

So I have been searching for information regarding how to add semaphore signals to a heritage railway. The UK specific wiki page on signals only really gives information on light signals using GB-NR: https://wiki.openstreetmap.org/wiki/OpenRailwayMap/Tagging_in_the_United_Kingdom

The tags I think might apply are:

railway=signal
railway:signal:main:type=semaphore

The issue is for a heritage railway the signal does not fall under National Rail which is where:

railway:signal:main=GB-NR:main

Would make sense.

Also how do you specify the facing direction of the signal? Is it just railway:signal:direction? As the wiki seems to suggest that that tag relates instead to the side of the track the signal is on.

Thanks for your help in advance, I can re-explain if this confuses anyone.

Mein gott that’s unnecessarily complicated. That’s the sort of tagging that could only be invented by a trainspotte… …oh I see.