Fritz and the other chess programs such as Komodo, Houdin, etc. offer numerous automated functions for extending the openings book with selected games. The program evaluates the information and embedded statistics and matches everything to the way the program plays.

 

What is less known is the option to extend and modify the openings book directly by inputting moves yourself. A right click in the tree view starts a little context menu which allows you to extend the book by personally inputting moves via the entry “Allow Move Adding”.

 

Important: After inputting the moves you want, you absolutely have to deactivate the option so as to prevent the book from being extended involuntarily.