List of portability issues

Hello, I haven't found in the php.net site a single list of all the things to avoid when writing php code that will run on every OS/httpd server combination (for example: 1) be careful with / and \ when hardcoding paths, 2) some printing functions (see a recent thread) are available on Win* servers 3) etc, etc.... Does such a list exists? where? TIA, Marco Fioretti -- Real Programmers don't play tennis, or any other sport that requires you to change clothes. Mountain climbing is OK, and real programmers wear their climbing boots to work in case a mountain should suddenly spring up in the middle of the machine room.