.CTO

.CTO file extension

This is the basic program to work with .CTO extension

ChessBase Light 2007

ChessBase Light 2007 ChessBase openings book

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

.CTO extension is also supported by the following programs:

ChessBase 9

ChessBase 9 ChessBase openings book

ChessBase

ChessBase ChessBase openings book

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

ChessBase Reader ChessBase openings book

It allows you to watch the presenter talk whilst the chessboard.