I think a more important question is whether or not the content on a dynamic page such as .php will be indexed. Basically, the spiders don't see the content derived from the PHP script. So, worrying about the identifying characters after the "?" is really missing the point.

In other words, whether or not the spider will read beyond the "?" has absolutely no relation to it being able to index what you think is on the page.

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DrTandem's San Diego Web Page Design, drtandem.com