As some of you may have realised I am having one or two understanding issues with some of PHP at the moment. I have been reading a book and I am finding the custom session handler part confusing.

I have copied code from the book which overrides the six functions that need to be overridden. I have passed these function names to the set_save_handler function which, as I understand it, sets them up as callbacks. My question is that I am not clear as to which methods to call to use them. I can work out that session_start() calls the open function I have declared but which of the session functions allow the rest to be used.

I have searched the php function reference and can't find the info I am after. Can anyone give me a definite mapping for the functions mentioned please.