Tom There are three data points - the 'Universal time' (at latitude 0 or GMT) and 'the offset' to calculate 'local time'.
It seems to me that the EHR will probably be based on local time - and recording the offset once per the transaction would give the absolute time of an event. This would deal with key events occuring over the period of change to day light saving (which could be important from a decsions support point of view) and the timing of events when someone is travelling and has had treatments in different countries - probably less important. Sam > -----Original Message----- > From: owner-openehr-technical at openehr.org > [mailto:owner-openehr-technical at openehr.org]On Behalf Of Thomas Beale > Sent: Friday, 12 July 2002 1:57 PM > To: open-ehr technical > Subject: new data type class proposal > > > > Naturally just as we have released a version of the data types, I > realised there was a class which should have been included! > > I propose to add an abstract parent of the classes DV_DATE, DV_TIME, > DV_DATE_TIME, called DV_REAL_WORLD_TIME. Its only features at the moment > are timezone: DV_DURATION, and the invariant for timezone guaranteeing > that it is within -1200 - +1200. The reasons I propose to add it are: > > - it captures the timezone and any other real world time characteristic > we think of in one place > - prevents the 3-fold repetition of timezone semantics in the 3 > subtypes, which was the previous situation > - provides a useful class for implementors to hang other real world time > implementation features off > - correctly differentiates the 3 absolute types based on real world time > from the 4th time type, DV_DURATION, which does not include any > real-world time semantics > - it makes no difference to the concrete date/time types - the final > result is still the same as in version 1.41 of the specification. > > I could not think of a better name than "real world time". Other > contenders are perhaps "Calendar time" (however, calendars are really > about years/months/dates) and "Universal time", which is defined as time > based on the rotiation of the earth (previously called Greenwich > mean time). > > A copy of the data types specification containing the change is at > http://www.deepthought.com.au/health/openEHR/data_types_1_42.pdf. > > Q1 - any objections to the addition of the class? > Q2 - any ideas for a better name? > > - thomas beale > > > > - > If you have any questions about using this list, > please send a message to d.lloyd at openehr.org > - If you have any questions about using this list, please send a message to d.lloyd at openehr.org
