Originally Posted by Manichean
Personally, I consider this iteration of the introduction to be an excellent candidate for a final version.
Absolutely fantastic job.
Thank you very much.
I wish, I had such excellent text available when I was starting to learn Regular Expressions. It was not using Calibre, but manipulating texts in various advanced text editors, such as TextPad on Windows or, later, Vim. It took me many, *many* trials and errors(*), and many re-reads of cryptic, very condensed manuals to discover things that you describe. Then I found the book "Mastering Regular expressions" ;-)
The book is excellent, but this Introduction is about the maximum that a person that has never used REs before can (and is willing) to digest. Even more important is, that most users will never require more than you describe, even if they do fairly advanced stuff with RE magic.
I think you should definitely consider becoming technical writer. Very few people can understand complicated technical issues AND present them in such a clear, concise manner. Knowing what can be left out for your particular audience is perhaps the most difficult thing for technical writer.
You have just made Calibre much more useful tool for many people.
(*) yes, I did fail spectacularly many times and I did take notes ;-)