This is a horrible book, that is cluttered with numerous errors. If you want to learn about socket programming in C, you might find that UNP would do well to teach you, shown here http://goo.gl/uqCP8
So, contextually, we're referring to C here, wherein these terms refer to Implementation Defined Behaviour, and Undefined Behaviour. Allowing beginners to understand such terms early on would help, immensely.
10 years suggests nothing, really. If "int x; What type is &x", "int x[5]; What type is x? What type is &x?" manages to confuse you, I suggest you re-learn C, before authoring this book of yours.