Wednesday, May 1, 2002

Mick’s travel tricks: dealing with time zones


By Mick Moignard

Many of you will know that time zone stuff in Notes can be a real minefield. Not because there are any major issues in Notes, but because the whole time zone thing itself is a minefield. You only have to go to Knowledgebase (at and see the number of items in there about time zone related issues to see the size of the problem. I'm not going to spend a lot of time in this article explaining how Notes does all the time zone stuff. What I want to do is explain how I use it. But we do need just a little bit of background, and I'll point out sources of further information.

Just a bit of background

First, I'll go over how Notes stores dates and times. This is reviewed in detail in Knowledgebase 169640 (at <a href=""></a>), which explains how to read a raw Notes date-time field value. While this explanation uses the database replica-id value as an example, it applies to all date-time values. The replica ID itself is just a datetime field and can be seen in its un-interpreted hex string form in the Notes User Interface. Look at a Notes database with NotesPeek to see raw date-time field values.

Knowledgebase 169640 explains that any date-time field value is actually stored as a time value, corrected via the local time zone settings to GMT (Greenwich Mean Time), together with a time zone offset value. To cope with the half and quater-hour time zones, it stores a time zone as an offset from GMT in hours, half hours, and quarter hours, and it doesn't store the name of the time zone. So 11:00 UK time and 06:00 New York time will both be recorded as the same time-value, but with different time zone offsets. In this way, Notes is able to relate any two time-date values to each other with certainty and to display a time correctly, regardless of the client or server's time zone settings.

The next piece is the client and server time zone settings. It's really important to get these set correctly because they're used as the basis for date-time value storage as well as for display. The server's time zone settings are made on the server document Basics tab in the Server Location information, as seen in Figure A.


The server's time zone settings are made on the server document Basics tab. (click for larger image)

Make sure that the time zone and daylight savings time rules are correctly set. At this point, I'm going to make a recommendation that you read Dave Delay's Iris Today article from March 2001, available either on or in Knowledgebase item 180001 (at <a href=""></a>). This explains exactly how to set these things up, and why, which makes it pointless to explain further here. But one place I differ from him is where he says that with the Notes R5 and above client, the best thing to do is to tell it, in Location documents, to have Notes track the Operating System--in this case, Windows--time zones.