Norton Commander Extension
Norton Commander is a file manager which was originally released by Peter Norton which was then in turn purchased by Symantec and was used for file management under DOS making use of two panes being visible at all times which made the copying of files from one drive to another easier. In 1998 the last version that supported DOS was released.
In 1996 the first Windows compatible version was released which ran under Windows 95 later versions also supported Windows 2000 plus certain functions from Windows XP and Vista.
Due to the ease of file management using Norton Commander many other programs use a similar format best known amongst them are Total Commander and Directory Opus.
Files edited by Norton Commander become the .ext file extension these have usually had the attributes etc changed.
» Norton Commander
How to open .ext files?
Software to open .ext files
What are .ext files