RE: Are date ranges half-open?

[Frank.Dawson@xxxxxxxxx]

> I've always though of the span of time of an event as a half-open
> interval. That is, the event includes the start time but does 
> not include
> the end time -- it ends some infintesimal moment before.
> 
> But Frank suggested in an example in a previous thread that 
> an event of a
> duration of one day is represented as:
> 
> DTSTART;VALUE=DATE:20010328
> DTEND;VALUE=DATE:20010328      
> 

If the end date is the same as the start date, then it still starts on the
28th. 

So, you are saying that this is the same as an event with just the DTSTART?
Right? RFC2445 states in the definition of DTSTART that this condition is
the same as an event that doesn't take up any time. So, I would say that my
example specifies such a condition.

Your comment about viewing DTEND as not being inclusive seems correct. So to
take up a day, the DTEND value should have been the 29th. But I still think
that this is the same as a DURATION value of P1D ;-)

-- Frank