>Do you mean "scrap"? Or is it possible to colour by map? I'm asking because AFAIK it isn't possible to include scraps from different projections in the same map.

You can colour the map-foreground by altitude, scrap or map (5.3.11 Therion Book pg 54).

You can have multiple maps per pdf output of the same projection, or include previously generated pdf outputs (as a flat image via map-image statement) in a new output.  This is how to get Therion to put generate outputs with differing projections in the same output.

When contemplating ‘colour by altitude’ it is important to note that the resolution is never better than ‘scrap by scrap’ – ie each scrap can only have one altitude colour.

Bruce