BModel

BModel (bsp model) or submodel is a model constructed in level editor out of brushes or patches. Doors, trains, platforms are bmodels.

Benefits

• very fast to render
• easy to construct in level editor (dont need a third party tools)
• can be lightmapped or lit dynamically (using lightgrid)
• supplied with level BSP file (also can make external bmodel which will have .BSP extension)
• can have triangle models attached

Drawbacks

• cannot be animated (only moved/rotated)
• complex models have very rough triangle mesh
• only simple models is easy to make