I think this is a pretty strait-forward question that a lot of others have probably come across, and I'm surprised that I have not gotten a reply. I guess to the end user it would not be possible to detect whether I used a server side scripting language to modify the channel data... and it is benign action of course I only want to track pages more accurately. But despite all that I still feel the need to ask before doing anything involving the code that G provides.

Does everyone understand the question? I have adsense ads in my site header, which I include() with php. Right now the header reports to it's own channel... "header" .. but I want it to report to the channel for each specific page. So I was thinking I could make a variable at the beginning of each page ... $chan-code ="whatever" and then insert that into the channel data ... or something....

There is no problem doing this. It is not important how the page is generated, only what is generated.