This book is a fantastic resource for beginning technical editors. It gives a great overview of the document production process. It has in-depth coversations regarding punctuation, grammar, and spelling. Would make a great supplmental resource to be used in conjunciton with another style guide. The book has a very robust glossary and detailed index. This one is going on my reference shelf.
Small note: this edition is from 2005, so much of the information regarding information management technology is already woefully out-of-date. For example, DITA was not mentioned. The principles in the book are still valid, but it would be nice to see a newer edition of the book with more recent technologies.