Hi all,
I'm studying a problem related to how we deal with the temporal extent in in GeoNetwork based on ISO 19139. Our construct seems to be different from what I read in Ron Lake's (BCC'd) blog on how time is to be formatted in GML:
http://geoweb.blog.com/494471/
I like his simple proposal, but I'm now wondering what the best approach is.
Also, the simple approach doesn't seem to work in GeoNetwork when I tested it. The begin element is removed automatically for some reason and when validating, I get an error that the id attribute of the gml:TimePeriod element is missing... That wasn't part of the particular example on Ron's website.
TimePeriods are defined in the same menner. A TimePeriod (a temporal duration or interval) can be expressed in a number of different ways to allow users to tradeoff between expressiveness and simplicity. These different forms include:
<gml:TimePeriod>
<gml:begin>2003-02-13T12:28-08:00</gml:begin>
<gml:end>2003-02-13T12:30-08:00</gml:end>
<gml:TimePeriod>
Here the begin, end elements are timePositions and carry the same attributes as the timePosition discussed above.
<gml:TimePeriod>
<gml:beginPosition>
<gml:TimeInstant>
<gml:timePosition>2003-02-13T12:28-08:00</gml:timePosition>
</gml:TimeInstant>
</gml:beginPosition>
</gml:endPosition xlink:href = "... #T001"/>
<gml:TimePeriod>
My feeling on the whole thing is that this is a pain for interoperability 
However, I want to make sure we end up with a suitable implementation.
Hope someone can provide feedback on this.
Ciao,
Jeroen