Issues related to signed/negative duration

[William Cox <wtcox@CoxSoftwareArchitects.com>]

I'm sending this to the entire TC. Your insights will be welcome.

I had noticed that ISO8601 and RFC 5545 and 6321 specify the Duration string patterns differently: 8601 has an unsigned duration, and 5545 an optional sign.

In WS-Calendar we used the 5545 duration with an optional "+"/"-" as we were extending 5545/6321.

In the PIM we are using the full 8601 set of duration strings (the language specifies more than 5545 and more than XSD, with incomplete overlap of 5545 and XSD).  This is important to use the full expressive power; an alternative that might be considered would be to specify the union of XSD and 5545 duration, but that's not where we are - and I think CS01 should stick with the 8601 patterns.

The problem comes when we specify a gap. In WS-Calendar 1.0 it's signed, with semantics for a negative gap. And the duration in Interval and Tolerance is (in WS-Calendar 1.0) of the "well-known element from iCalendar and XCAL".  We well understood the nature of a negative gap (see line 423 WS-Calendar
"Gap may be positive or negative. In the examples below, the Gap, when present, is 20 minutes.")

Elsewhere in WS-Calendar, in Tolerance the tolerances should be (and appear to be) unsigned.

This suggests that we should record an issue on WS-Calendar 1.0 with respect to the signed/unsigned nature of duration for intervals and tolerance (or in the ugly alternative, a lengthy description about what a negative duration interval or tolerance means).

In Jira item https://issues.oasis-open.org/browse/WSCALENDAR-526 I've collected most of these issues as subtasks against PIM WD11.

Thanks!

bill

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William Cox
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