Subject: Confusion regarding user interpretations for times spanning midni ght

From: "David Lowndes" <[email-masked]>
Date: Tue, 7 Mar 2000 14:07:55 -0000

The draft-ietf-policy-core-info-model-03 document says this:

   When a range spans midnight, it by definition includes parts of two
   successive days.  When one of these days is also selected by either
   the MonthOfYearMask, DayOfMonthMask, and/or DayOfWeekMask, but the
   other day is not, then the policy is active only during the portion of
   the range that falls on the selected day.  For example, if the range
   extends from 2100 until 0800, and the day of week mask selects Monday
   and Tuesday, then the policy is active during the following three
   intervals:

       From midnight Sunday until 0800 Monday;
       From 2100 Monday until 0800 Tuesday;
       From 2100 Tuesday until 23:59:59 Tuesday.

This is a logical interpretation of the underlying attributes. However it's
not necessarily a logical interpretation for someone who has to enter and
maintain this data.

I should add that we have a 50:50 split in the interpretation of this
in-house. We all agree that the proposed standard is the simple way of
interpreting the underlying data, but half of us feel that it's misleading
from a user's perspective.

Given a slightly simpler example, to allow a policy to start on a Saturday
at 22:00 and finish on the Sunday at 4:00, a normal user would expect that
entering 2 items: a day mask of Saturday, and a time range of 220000:040000
would fully specify the range. After all, surely that is why you've allowed
times to span midnight?

Under the proposed standard interpretation this will actually mean that the
example policy is valid on 2 discontinuous time periods:

An unwanted period:	Saturday 000000:040000
A wanted period:		Saturday 220000:235959

Furthermore, to obtain the user's required time period they have to specify
2 periods: Saturday 220000:235959 and Sunday 000000:040000, which is rather
long-winded and not particularly intuitive. If this is case, we can't see
the point in allowing times to span midnight.

You could argue that it's not the standard's responsibility to be concerned
with user-interface issues. However, if the standard makes it impossible to
convey users intentions in an unambiguous manner, then we think it is a
matter of some concern.

Any thoughts?

David Lowndes

---

From: John Schnizlein <[email-masked]>
Date: Tue, 07 Mar 2000 09:59:05 -0500

David,
How does the Calendar and Scheduling WG deal with issues like this?
Would you be satisfied if we followed their lead rather than
specifying schedule semantics in the policy WG?
John

At 02:07 PM 03/07/2000 +0000, David Lowndes wrote:
>...