[SensorML] SweCommon: Time

Johannes Echterhoff echterhoff at uni-muenster.de
Thu Jun 21 10:27:03 EDT 2007


I have a question concerning the possible meanings of swe:Time. Such an 
element can have four different representations: a string (before, 
after, now or unknown from gml:TimeIndeterminateValueType), a double, 
xs:data, xs:time or xs:dateTime.

The meaning of each of the possible representations is quite different:

    * gml:TimeIndeterminateValueType does not provide a specific time
      instance but rather an indeterminate value (as the name says)
    * The double value would always have to be computed with respect to
      the given referenceFrame. This could result in a time instance but
      could also be a duration or recurring time depending on the
      reference frame, or am I missing something?
    * xs:date defines a duration (one-day long) at a specific date (e.g.
    * xs:time represents an instant of time that recurs every day.
    * xs:dateTime finally represents a specific instance of time.

My question is: was it intended to allow all of these different meanings 
for the swe:Time element? I thought that swe:Time would represent an 
instance of time in the end, but now I am no longer sure about that.

Best regards,

Johannes Echterhoff
Institute for Geoinformatics (IfGI), University of Muenster, Germany
Robert-Koch-Str. 26-28, D - 48149 Muenster

Fon: +49 (0)251 83 39761
Fax: +49 (0)251 83 39763

IfGI-site: http://ifgi.uni-muenster.de/

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