CUIX file contains data related to user AutoCAD software user interface. CUIX file format is the official successor of older CUI format. MNU and NS are now also obsolete, as the information about program workspace they contained are now intergrated into CUIX file.

AutoCAD reads default setting from acad.cuix file upon starting. Custo msertting can be created using custom user interface (CUI) editor and seved in CUIX file. Users can configure such setting as window panes, toolbars and menu elements.