.CTO file extension

This is the basic program to work with .CTO extension

ChessBase Light 2007 ChessBase openings book

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

.CTO extension is also supported by the following programs:

ChessBase 9 ChessBase openings book

ChessBase ChessBase openings book

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

ChessBase Reader ChessBase openings book

Open chess games database files and play through the games.