# RE: Order relation on gMonthDay, gMonth, gDay

```James, you said...
"If gMonthDay values are considered as periods of time using an arbitrary leap year, ..."

Similarly, for gMonth and gDay."

I agree for gMonthDay since --2-29 is a legal value.  But for gMonth there is no connection with leap year.  It's just the start of the month in any year.  For gDay it's "... arbitrary year and month in which the date occurs".

All the best, Ashok
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-----Original Message-----
From: James Clark [mailto:jjc@jclark.com]
Sent: Tuesday, April 23, 2002 10:16 PM
Subject: Order relation on gMonthDay, gMonth, gDay

The order relation on date is specified as:

"If date values are considered as periods of time, the order relation on
date values is the order relation on their starting instants."

This makes sense to me.

The order relation on time is specified as:

"The order relation on time values is the Order relation on dateTime
(§3.2.7.3) using an arbitrary date."

This also makes sense to me.

Now consider the order relation on eg gMonthDay:

"If gMonthDay values are considered as periods of time, the order relation
on gMonthDay values is the order relation on their starting instants."

I don't think this is quite right.  A gMonthDay is not a single period of
time but a recurring period.  The dateTime ordering relation compares two
specific instants of time. Thus in order to turn a gMonthDay into a specific
instant of time, you need to use an arbitrary year (just as with time you
need to use an arbitrary date).  However, I'm guessing --02-29 is allowed as
a gMonthDay; if so, the year is not an arbitrary year but an arbitrary leap
year.

So the spec should say something like:

"If gMonthDay values are considered as periods of time using an arbitrary
leap year, ..."

Similarly, for gMonth and gDay.

James
```

Received on Saturday, 27 April 2002 12:53:01 UTC