Level
From ZDoom Wiki
A level is any given area where a game takes place. Doom and Heretic use an ExMx format for maps, and Doom II, Hexen and Strife use a MapXX format. The latter two of these use a hub system. ZDoom can use any 8 character string as a level name by modifying the MAPINFO lump, and it also allows for the use of hubs.
Each map contains several lumps:
