| PHP handles it exactly the same as if it was a straight html file. It's governed by the http standard, i suggest you look into that, unfortunately I dont know anything beyond that. I wouldnt be surpised if the client sent a request that had a special "resource id" or something, and then sent another request with the actual file contents and in the header the corresponding "resource id" but again, i believe thats part of the http standard, if not , its closely related, and i suggest you start there though.
cheers (i know that wasnt the answer you wanted and i'm sorry i cant help more than that)
-Dan |