Time differences

Having spent the better part of the last 18 months in a rather different time zone to GMT, I have got rather used to attempting (and I do stress 'attempting') to work out the time differences for whereever I may be trying to contact. In Australia and New Zealand it was, generally, rather simple. When I got to NZ it was 13 hours difference, then it became summer time in Britain and winter time in NZ taking it down to a manageable 11 hours. In Victoria (and Queensland when I was there) was a rather delectable 9 hours which changed back to 11 last winter. Easy-peasy. Then I came back home and TAB, with whom I am still in quite regular contact, was in Adelaide. They were only 9 1/2 hours ahead of GMT and now we've gone into summertime and they're 8 1/2 hours, I think. With my husband still in Victoria I have to remember that they're 9 hours ahead and thankfully I no longer know anyone in Queensland as they don't have daylight savings and so are something like 10 hours ahead. It all really rather confuses me when they throw in daylight savings and things. What brought this on was that when I logged onto blogger.com it very helpfully told me that there's a scheduled outage at 4pm PDT. Excuse me for being a little bit dim on occasion (well, ok, pretty much constantly) but what the hell is PDT? GMT - Grenwich Mean Time. Fine. But PDT? Pacific Down Time? Pretty Dirty Time? PisseD off Time? And, given that I don't know where in the world PDT relates to (am guessing America but that would spoil the rant a little) the fact that at 4pm their time they're having a scheduled outage means diddly-squat to me! I logged on at 2 minutes to the hour and didn't know if I'd be thrown off the site almost immediately or not. I've actually had to go to The World Clock to double check which cities are in the time zone that have just passed 4pm(which, for those interested are Edmonton, Denver, Guatemala, San Salvador, Tegucigalpa (??) and Managua) in an attempt to work out if I would be in danger. I figured I've probably got just under an hour until LA and San Francisco arrive at tea time. I think I may have lost the plot somewhere along the line. Or maybe that should be the time zone?