From: Nicholas Avenell <nicholas@englishcity.com>

Date: 14 March 2011 11:39:47 GMT

Subject: On Timezones, Daylight Savings, and how this works with the Calendar

Simple and quick version:

• The Calendar on the website displays the time your class will start in the place you've got your time set to.
• Check your classes the week before, and notify someone if something's up. It is your responsibility to do this.
• This goes double, triple and quadruple for anything scheduled around Daylight Savings Time (Mid -> end of march, End of october to first week of November)
• Someone should have noticed Ben Franklin was joking.

Longer and more florid version:

Daylight Savings Time was invented in 1784 by Benjamin Franklin, who was joking. Sadly, someone more recently failed to get the joke, and here we are.

On the site, we store dates and times in Universal Coordinated Time (UTC, which stands for Universal Coordinated time when translated into French.) (Also known as GMT, Zulu, Zero Time and a few other militaryesque variations on the theme). This doesn't generally matter to you, but might help.

The website, when it shows a date, magically converts it from UTC into whatever you have set as your current timezone. So for me, it'll currently show London time, for someone set to Paris time it'll show what time it is in Paris, for someone in Las Vegas it'll show you what time it will be in Las Vegas when the lesson starts. You might be used to thinking about your timekeeping in-world in Server/Linden Time, which corresponds exactly with San Francisco time, with all the daylight savings and such that this entails. 

So, the time on the calendar reflects the time that the class starts in the timezone you've asked it to show.

The advanced scheduler is a bit more complicated, especially when you ask it to schedule things across daylight savings changes. It *should* take into account timezone changes, but it will do so of whoever schedules the classes, rather than whoever is teaching them. This means if Nicholas in London schedules "Introduction To Cake Baking" running every day at 9am UTC from the 10th March to 15th April, then from the 27th March they'll be scheduled at 8am UTC, because that's when london goes to Daylight Savings Time. This will confuse people in San Francisco, because their daylight savings starts on the 13th, so from there perspective it'll be 1am to start with, then down to midnight between the 14th and 27th March (While SF is on Daylight Savings and London is not) and then back to 1am when Daylight Savings kicks in in SF.

That paragraph in diagram form:

So, in conclusion, timezones are complicated enough as they are, and Daylight Savings make them even more so. The system tries to help as much as it can, but there is no real way to make it work perfectly for everybody, so please check your classes are when you think they are.

Yours simplifyingly,

-- N

-- 

Nicholas Avenell

Lead Developer -- Languagelab.com

twitter: @aquarion, SL: Jascain Switchblade

nicholas@languagelab.com