FileInfo.com - The File Extensions Resource

.EXT File Extension

File Type	Norton Commander Extension
File Format	File
Common?	No
File Description	Extension file used by Norton Commander for DOS / Windows 95; allowed users to modify files, such as change file attributes and synchronize directories, using a text-based interface.
Program(s) that open ext files	Windows: Norton Commander

Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/ext