I have tested and verified the information in this document to the best of my ability, but you may find that features have changed (or even that I have made mistakes!). Please let me know about any errors you find, as well as your suggestions for future editions, by writing to:
Feel free to send comments or ask technical questions about this document to the same address.
I also have a web page for the document, where I list errata, examples, or any additional information. You can access this page at: