Zend API / PHP Internals Reference Manual

I'm looking for a Reference Manual for the Zend API and/or PHP Internals. I've found about forty 'leven "how-to" and "learn by example" talks, slide-shows, tutorials, etc for writing a PHP extension. Don't get me wrong, these are great! But they leave me with questions about a bunch of macros and ton of code, and while I *can* read C source, and puzzle my way through it eventually, more or less, to some degree... Well, I'd be a whole lot better off if I found the moral equivalent of http://php.net/manual only for "Internals" Did I just miss it, or is it a pipe dream, or is it just not seen to be useful? -- Like Music? http://l-i-e.com/artists.htm