Yes, but the book also has enough inaccuracies as to make it... I don't know what. For example, in the first chapter the author says "no one knows what a session is," which is patently false. I myself implemented control logic in telco equipment to respond to X.225 compliant messages to change the state of an abstract state machine used on either side of the connection. And while I'm sure it's possible to use CONS or CLNP to communicate with a CEEFAX terminal, that is far from the only use to which the various OSI compliant protocols were put.

Just because you don't understand something, that doesn't mean it's bad.