Rails default timestamps in PHP

In rails created_at and updated_at timestamps are saved in the below开发者_StackOverflow社区 format. What is it "called" and how can I replicated it in PHP?

2011-07-21 15:34:58.885171+0000

Thankful for all input!

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I'm not entirely sure what exactly that format is called, but PHP doesn't have a predefined constant for it, so you need to create it yourself:

date('Y-m-d H:i:s.uO')

I seem to vaguely remember that .u will always equal .00000 in current PHP versions though.