Files with nai file extension can be found as old files from WinInstall program. Obsolete.
NAI file extension - WinINSTALL data
What is nai file? How to open nai files?
File type specification:
The nai file extension was years ago used for one of the files from WinInstall program by Symantec.
Seems like the program was discontinued long ago, and thus this file type is more or less obsolete.
This nai 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.