An xxt file extension is sometimes used for DLL (Dynamic Link Library) files.
XXT file extension - Dynamic Link Library
What is xxt file? How to open xxt files?
File type specification:
The xxt file extension is sometimes used for Dynamic Link Library, but default file extension for it is DLL file extension.
Most likely some old format without support. No further information could be found.
This xxt file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.