Question: I'm looking at the PayPal `IPN docs`, and it says the `datetime` stamps of their strings are formatted as:

```
HH:MM:SS DD Mmm YY, YYYY PST

```

So year is specified twice?

Once in double digits, and another with 4 digits? 

This looks bizarre.

Answer: 
this is the correct format according to their documentation - 2010-03-27T12:34:49Z
so it is - YYYY-MM-DDTHH:MM:SSZ (I don't know what the T in the middle and Z is but it's constant for all the dates)
I've created PayPal NVP library in Java, so if you want to check how it works, or use it, 
you are more than welcome. it's on sourceforge - payapal-nvp.sourceforge.net
Actually, I think the right format is: yyyy-MM-ddTHH:MM:ssZ

The case is important.