Can't you understand it John?
If it were clearly understandable, we wouldn't be having this discussion, and we certainly wouldn't be seeing people giving opposite answers (seemingly about 37.5% 'Up' and 62.5% 'Down' so far - which is hardly a 'consensus')....
I would say it only relates to the door, so should be up.
I would have an uninformed guess at down arrow ...
Arrow up, if there was a step down the other side of the door then arrow down to warn of that
Arrow should point down, ...
To comply to BS I would say upwards.
It's simple, follow the arrow.
I wouldn't necessarily say that (if one even bothered to think about the arrows) following an arrow which was pointing at a ceiling would necessarilybe all that "simple"/obvious to everyone.
Given RF's question, everything I've said relates to
signs above doors. As I have said, if someone needs to escape and sees a door with an illuminated sign, they will go through it, regardless of any arrows.
As you go on to say, once through the door, if what people should then do is not then obvious, further arrows will be useful (possibly 'necessary') - particularly if there are left/right choices to be made (other than in basements/cellars, it would be extremely unusual for 'up' to be an appropriate escape route - so, in any other situation, further up/down arrows probably are not very useful).
As above, I don't think that many people would, particularly 'in the heat of the moment' take any notice of the direction of an arrow on a sign above a door - but, since an arrow is 'required' one pointing down (i.e. pointing at the door) would seem the most obvious to me.
A sign over a door leading immediately to (upward) 'escape stairs' from a basement is a special case. Given that the first thing escapers have to do is to go through the door, an arrow pointing down (towards the door) would still seem the most logical to me, but I can see the argument for an 'up' arrow (particularly if the stairs start immediately beyond the door) - although I doubt that many people would even think about the significance of that.
Before one has gone through the door, left/right/diagonal arrows are not really relevant, and may well not really be understood.
When above a door, an 'up' arrow (i.e. pointing away from the door) is perhaps the one which (if noticed and thought about) might result in the most confusion. People do seem to generally understand that an 'up arrow' on a road sign means 'forward', but the irony (confusing) there is that, with road signs, people seem to understand that a 'down arrow' refers to travel in the opposite direction to which one is facing (i.e. 'backwards'), whereas the 'down arrow' above a door is being used to refer to moving 'forwards'.
In summary, personal view (obviously not compliant with regs) is that if the first thing person needs to do to escape is to go through the door, then all that matters is that the door is identified by an illuminated sign, and arrows pointing in any direction willnot really add anything to thast.
Kind Regards, John