.CKO file extension

This is the basic program to work with .CKO extension

ChessBase Light 2007 ChessBase Opening Key

The program works with the following extensions: ck1, cbs, ck2, cko, ck3, cba, ckn, cbb, cp1, cbc, cp2, cbe, cp3, cbf, cpn, cpo, cbh, ctb, cbm, ctg, cbp, cto, cbt, pgi, cbv, pgn, cib, cbz, cit and cbgi

.CKO extension is also supported by the following programs:

ChessBase 9 ChessBase Opening Key

ChessBase ChessBase Opening Key

ChessBase 13 is a personal, stand-alone chess database.

ChessBase Reader ChessBase Opening Key

Open chess games database files and play through the games.