What is shown on SkyDemon charts are the maximum elevation figures for an area. That is NOT the same as a minimum safe altitude; the pilot must decide their own minimum safe altitude based on the maximum elevation figure. The MEF shown on SkyDemon charts are derived from the highest terrain in the area, and the highest obstacle in the area, simple as that.
SkyDemon warnings cannot make the entire screen go red. TerrainSafe is not really related to warnings directly but it does show you terrain that is likely to be a threat because it's close to (or above) your current level.

Hello

Just a quick Q.. I note the MSA numbers on SD are different from the CAA 1:50,000 maps.. can I confirm that skydemon uses these numbers and then looks at the UK rules of the air then works out whether you are flying above a town for example and then applies 1000 feet for example?

Also even though I have the terrain and obstructions alarms setup is there a way that the actual screen will go red for example.. I presume the Mountain Terrain view shows this?

thank you

Karl