START MAP
From 3DGE Wiki
Usage:
START_MAP <Map Name>
Description:
All triggers after this tag are associated with the specified map number.
Details:
<Map Name> is the same as the lump name, for example e#m# for DOOM1, and map## for DOOM2.
If you use the keyword "ALL" (without quotes) instead of a mapname then the trigger will apply to ALL the maps, almost like a global function.