World Loading Unit
World Loading Units (WLUs) are layers containing entities. They can be loaded and unloaded on demand as long as the specific WLU is currently not loaded yet.
Each entity in a WLU has a defined ID, position and orientation, and, like all other entities, uses components to define its properties. WLUs are mostly used to load mission-specific objects. Additionally, the game world itself is made up of WLUs as well.
WLU files are located in the "worlds/windy_city/generated/wlu" directory inside the game archives and use the file extension "xml.data.fcb", whereas the file name must begin with "wlu_data_".
WLUs can be loaded by name using the LoadMissionLayer function. Entities inside of WLUs can be referred to at any time, but will not be valid until the corresponding WLU has been loaded.