[CentOS] tzdata, Greenwich zone: URGENT!

>        Checking /usr/share/zoneinfo/, i saw GMT, GMT0, GMT-0, GMT+0, UTC &
> Greenwich.  Does anybody knows the differences between all these or could
> provide a link to a reference?  I found some infos but nothing that explains
> the subtlety.

Basicly it comes down to GMT being based on the rotation of the earth
around its axis and the sun (which isn't completely regular) and UTC
being based on a Cesium atomic clock (which is far more accurate and
regular). UTC is regularly modified with "leap seconds" so that it
matches up to GMT to be the standard for date/time stamps. Also, UTC
is the authoriative measurement for calculations involving duration.

plagarised from

http://people.etango.com/~markm/archives/2004/02/29/gmt_vs_utc.html

not sure about the GMT-0 GMT+0 or GMT0

mike