Is PHP Timezones getTransitions credible?

Question

Have you had any problems with converting time in PHP through the getTransitions function?

I am trying to convert Argentine date to GMT. If I look at the transition array, I get:

.... [63] => Array ( [ts] => 1287284400 [time] => 2010-10-17T03:00:00+0000 [offset] => -7200 [isdst] => 1 [abbr] => ARST ) [64] => Array ( [ts] => 1300586400 [time] => 2011-03-20T02:00:00+0000 [offset] => -10800 [isdst] => [abbr] => ART ) ... 

which means, if I'm not mistaken, from 2010-10-17 to 2011-03-20 the difference in seconds of the Argentine date, compared to the GMT equivalent, it will be -7.200 (2 hours).

But reality - the current displacement - four hours.

Please, what am I missing? Sorry if this looks like homework, but before writing a question, I searched and tried a lot.

Thanks.

Edit: Thanks for the answers. I understand that PHP transitions are hardcoded in the PHP dll.s settings, so if any government decides to change its temporary policies, getTransitions will become obsolete if you do not update your PHP installation (something is not so easy when you have a production environment or you use shared hosting).

So, a new question: is there any web service or dynamic API for determining the current time delay (or future delay) for a specific time zone, for example http://worldtimeengine.com/api/ but maybe for free?

Answer 1

I'm not sure if this is wrong?

http://en.wikipedia.org/wiki/Time_in_Argentina

States that are usually in Argentina at UTC -3, and that they sometimes observe daylight saving time. What would make him UTC -2?

On the other hand, the article says that they currently do not observe daylight saving time in order to save them at UTC-3 (-10800)? Perhaps your time database is old?