What is wid?

...so I'm generating player embed code in php, like the one you get in the flash player, it looks something like this:

<object name="kaltura_player_1256711243" id="kaltura_player_1256711243" type="application/x-shockwave-flash" allowScriptAccess="always" allowNetworking="all" allowFullScreen="true" height="395" width="640" data="http://example.com/kalturaCE/index.php/kwidget/wid/wxhg1yjp9k/uiconf_id/48412">...bunch of params...</object>

to break it down, it's

<object name="kaltura_player_{unix timestamp}" id="kaltura_player_{unix timestamp}" type="application/x-shockwave-flash" allowScriptAccess="always" allowNetworking="all" allowFullScreen="true" height="{player height}" width="{player width}" data="http://{your site}.com/kalturaCE/index.php/kwidget/wid/{???}/uiconf_id/{custom player id}">...bunch of params...</object>

How can I generate the wid?? This number is unique every page refresh.
I know i can do the wid/_{partner id}... but I want to know how the wid is generated.

Thanks folks!