GML Geography Mark-Up Language: Foundation for the Geo-Web, by Ron Lake, David S. Burggraf, Milan Trninic, Laurie Rae; publ. by Wiley
With a chief writer who was responsible for much of the GML standard, this book is an indispensible reference for those who wish to create their own GML application schema, or wish to have a better understanding of GML.
This is the only book that I have found that gives more than a cursory mention of GML (Geography Mark-Up Language). It works as an excellent reference book, but also treats the various concepts in a logical manner. Although the content might seem drier than most geo-web books, it should not be confused with an alphabetical reference manual. GML is one of the more complex geographical data formats, and the authors take each concept and explain why it is implemented the way it is. In fact, many of the sub-section titles are in the form of questions.
The introduction (67 pages) explains GML's place, deployment, and example applications. This is followed by the main reference section of the book (254 pages). The reference section takes each group of concepts (features, coordinate reference systems, etc) a chapter at a time. The four appendices cover the core schemas, resources, a glossary, and a quick XMLSpy tutorial.
The book includes lots of source code examples and many diagrams. It does not have any color, but the subject matter does not require it.
This book is strongly recommended for anyone intending to write a GML application schema. It is also recommended if you intend to know more than the very basics about GML, or if you wish to have a better understanding of the GML schema and design philosophy.