Status of undocumented language constructs

Hi there, I'm in the process of (re)building a PHP syntax highlighter. I've been using both the doco, the Zend lexer/parser code, and the mailing lists as my reference, and I've been able to work out most things for myself. But I've found a few that I can't suss. Firstly, I can't find any descriptions of these constructs, even though Zend recognises them: - The "scope resolution" operator ::, which is given the endearing and cryptic token T_PAAMAYIM_NEKUDOTAYIM in the lexer. - declare - enddeclare - const - use Clearly, these aren't in common use, and not many people will suffer if I get it wrong, but I'd still like to know: - what version of PHP did these things appear? - what version of PHP did they get deprecated? Secondly, there's the status of string literals and the back-tick operator, and whether embedded newlines are supposed to be legal. I know they work, but are the following *supposed* to be legal, or not? "I am a multi line string" 'So am I' `echo exec me` Thanks, Gid