If you want a staircase with top and bottom landings, just select a U shaped staircase type and set the Turn stairs count / Turn step count to 1.

Yeah. That's what I did. I just thought the omission of a top and bottom option was strange. Now thinking about it, I see why the options you have were needed. Those couldn't work with the U type.

Adding information about the slope or pitch angle shouldn't be difficult except that this angle varies along square spiral staircases, but we could display an average angle for them.

θ = arctan (riser height/tread depth)

I don't see the need to complicate it any more than that.

Taking into account regulations is probably out of reach just because regulations are different from a country to the other, as Keet noticed also.

I think there will be a lot of common basic rules though. Max pitch. Min tread depth/width. Max riser height. Max steps in a single flight (i.e. between to landing zones). Min nosing. These could all be simple numerical min/max values that the user can configure for their own locale. Sure, the head height one was a bit more exotic, but I did say it was a stretch [:D]

One minor side niggle with the current version is the tread thickness maxing out at 30 mm. It is possible to approximate an open tread staircase by hiding the risers, but the 30 mm max tread depth means you can't emulate the kind of modern thick block floating staircase. A look at the code looks like this is an arbitrary figure you chose that felt right, but perhaps it is a limit forced by the code. It'd be nice to have the option to go higher.

Are you happy to accept patches to this plugin that add any of these things?