A text file that maps each Revit category or subcategory to a preconfigured layer name for the CAD software. For example - a Revit door object automatically maps to the A-DOOR layer in AutoCAD. The layer names are preconfigured in the text file - but

Revit is often used for designing buildings and creating 3D models of architectural designs. It allows architects to create detailed building designs, visualize the project in 3D, and produce detailed documentation and construction drawings.
Revit is a contraction of Revise-Instantly.