What is utmu parameter in google analytics __utm.gif request?

I am trying to make the google analytic __utm.gif request using php. I have broken all the variables and the only one which I don't know about is utmu parameter. It is not documented anywhere.

When I see a pageview tracking request it is appended to the end of request as &utmu=qB~ While doin开发者_如何学编程g ecommerce tracking it is appended as &utmu=qBAL~

Please help me with this.

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It is a bitmap of all of the methods used to build the request.

Source: http://glucik.blogspot.com/2011/02/utmu-google-analytics-request-parameter.html

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utmu doesn't actually contain anything of external meaning. Google uses it to store some internal values that help them improve ga.js. It's not required to make any functionality work, so, your PHP code doesn't need to account for it.

However, you should know there are already a few long-standing PHP-based Google Analytics projects, like Server Side Google Analytics (SSGA), as well as the semi-official Google Analytics for Mobile PHP and PHPGA.