ATY is used to identify a placeholder file for an association type after exporting a 3D concept map from 3D Topicscape to Windows folders and files.
It is used to provide the capability for a round-trip (export a Topicscape, change files and folders as desired and re-import it).
It is a text file that can be opened with notepad, but any change to its contents or name risks incorrect re-import.
See also: 3DT, FES, TPC