Do all ports handle mlook and tall skies the same?

[Doom_user]

A few days ago I started working on some tall skies and after running a few experiments I noticed that ZDoom allows you to see, exactly, an additional 99 pixels of sky texture when looking up,(which means the tall sky height for ZDoom is actually 227, not 240) I also noticed that 200 pixel tall sky textures aren't stretched and that they're drawn from the top as though they were 227 pixels tall, which means there's a 27 pixel range that standard skies cover that they won't. So basically my question is, do all ports handle mlook and tall skies in this manner, and if not, does anyone know the exact behavior of all the other ports? When I tried to duplicate my experiments in Legacy I ran into some problems...

[Quasar]

Eternity and zdoom's mlook are nearly identical except that you can look further down in zdoom. The upper limits are identical. As for Legacy, it does its own thing completely.

[iori]

Legacy uses 240px tall graphics for skies, or stretches the shorter sky presumably 40 px.