Like all books of the KBA dictionary series this book is no dictionary, however, its contents is structured a little to fit somehow the presented strategic concepts. What is haengma? I am not sure if even the Koreans really know it and I might be over-interpretating the contents. If I don't, then haengma is the concert of strategic concepts and strategic objects. Books even just about first order strategic concepts are still rare, so currently every book about second order strategic concepts, i.e. the cooperation of first order strategic concepts, should be considered a silver mine. In every chapter two or more strategic concepts are combined and related to the positions' strategic objects. Exceptionally a strategic object (like a huge moyo) might become so dominating that combining strategic concepts loses importance and each single strategic concept follows the key development.
If you had no idea what the book might be about, then it could be almost useless. You should have read Strategic Concepts of Go, Direction of Play, a shape book, etc. first. Even then trivial introductions might bore you until realizing that they serve as preparations to introduce a strategic concept that is going to be combined with other concepts or objects. Once you are aware of the general teaching approach, you might learn and improve considerably.
Principally, the book explains the key developments behind positions. Sometimes just a simple position but more frequently a sequence of moves is analysed. In the latter case the entire, preceding game is shown.
[Note: the following was added after the review was originally written.] In the review the term haengma is overinterpreted and it still is if described as "the development of strategic objects (like a group or a moyo) relative to a position's stones". Calling it "the development of a connection between two stones of one colour" may be an understatement, however.