Bit off topic perhaps - charting screens

[shouldbworking]

Not sure quite where to put this topic, but seeing as ships is my only frame of reference for it, here goes.

Short version - I'm wondering if those transparent screens you see in warship CICs are just straight perspex with grease pencils being used to write on them.

Long version - For a token bit of home decoration I'm getting one of those custom os maps made up and want to put a clear sheet over it that can be written on so I can trace out routes that I've explored (the idea being eventually I'll have covered it all), but want to make sure I get the right kit for the job. The only place I can think of where I've seen such a thing being used would be in films where positions and such are plotted on screens like the ones on the left in this picture http://upload.wikimedia.org/wikipedia/commons/f/ff...

[Fishtigua]

You may want to look at chinagraphic pencils and an acrylic cover.

http://www.mapsinternational.co.uk/finishes.asp