Another bundle of Pocket Guides and References from O'Reilly. Once again I have similar reservations about the first three. If you need a reference to any of these subjects a 'pocket' one hardly seems adequate. In the case of 'Extreme Programming' I have to say that I think its only value is to participants in Trivia quizzes. Extreme Programming is an Agile Methodology that you should understand in far more detail and if you do you would have no use for a pocket reference. I would welcome alternative perspectives on the first three books.
The next three seem different to me because in each case their subject matter hardly justifies more than a book of this size. If you need to know anything about RTF (Rich Text Format) I would think that this book will provide it. While Regular Expressions are important and turn up in many places a book this size is just about right.
If you are involved in open source or other forms of distributed development the CVS (Concurrent Version System) tool or something like it is just about essential. This small book is exactly what the user needs.
Note that in the last three cases it is entirely incidental that the book's size and format fits into an anorak pocket. The important thing is that the amount of material does not justify a larger book.
My final comment is that I have a general moan about almost all O'Reilly books; they do not like being open and make every effort to close unless manually restrained. Reference books should not do that, we almost always want our hands for other things when we are using them.