[Auscope-geosciml] An issue with ISO DataQuality and UnitsOfMeasure schema [SEC=UNCLASSIFIED]

Simon Cox simon.cox at jrc.ec.europa.eu
Mon Oct 12 04:49:52 EDT 2009

Ollie - Its all OK. 
You have to distinguish between the abstract model and the implementation. 
Sometimes they are related by a rule (e.g. the 19136 Annex E, or 19139
encoding rule), but sometimes they are just related by a 'mapping',
particularly if there is a pre-existing implementation that captures the
Thats what has happened in this case. 
It is also explained in Annex D of ISO 19136 (GML) where the GML
implementations of classes from ISO 19103 are explained. 

Simon Cox

European Commission, Joint Research Centre 
Institute for Environment and Sustainability 
Spatial Data Infrastructures Unit, TP 262 
Via E. Fermi, 2749, I-21027 Ispra (VA), Italy 
Tel: +39 0332 78 3652 
Fax: +39 0332 78 6325 
 <mailto:simon.cox at jrc.ec.europa.eu> mailto:simon.cox at jrc.ec.europa.eu 

SDI Unit:  <http://sdi.jrc.ec.europa.eu/> http://sdi.jrc.ec.europa.eu/ 
IES Institute:  <http://ies.jrc.ec.europa.eu/> http://ies.jrc.ec.europa.eu/ 
JRC:  <http://www.jrc.ec.europa.eu/> http://www.jrc.ec.europa.eu/




From: auscope-geosciml-bounces at lists.arcs.org.au
[mailto:auscope-geosciml-bounces at lists.arcs.org.au] On Behalf Of
Oliver.Raymond at ga.gov.au
Sent: Monday, 12 October 2009 08:53
To: auscope-geosciml at lists.arcs.org.au
Subject: [Auscope-geosciml] An issue with ISO DataQuality and UnitsOfMeasure

Hi all,


I have discovered a quirk/bug in the ISO DataQuality UML model and schemas
that we should be aware of, but should not be a show-stopper for us using
ISO DataQuality.


According to the ISO19115 UML model (see diagram below),
is of type gco:UnitOfMeasure (imported from ISO 19103).




However, contrary to the above UML diagram, the ISO19139 XML schema
implementation (gco/basicTypes.xsd) actually imports UnitOfMeasure from GML
(ISO 19136), not from ISO 19103.  As a result, the attributes of
DQ_QuantitativeResult/valueUnit that appear in the XML schema are quite
different to those shown in the ISO 19115 UML diagram.


Snippet from gml/units.xsd....


  <element name="unitOfMeasure" type="gml:UnitOfMeasureType">


      <documentation>The element gml:unitOfMeasure is a property element to
refer to a unit of measure. This is an empty element which carries a
reference to a unit of measure definition.</documentation>



  <complexType name="UnitOfMeasureType">


    <attribute name="uom" type="gml:UomIdentifier" use="required"/>


  <element name="UnitDefinition" type="gml:UnitDefinitionType"


      <documentation>A gml:UnitDefinition is a general definition of a unit
of measure. This generic element is used only for units for which no
relationship with other units or units systems is known.

The content model of gml:UnitDefinition adds three additional properties to
gml:Definition, gml:quantityType, gml:quantityTypeReference and

The gml:catalogSymbol property optionally gives the short symbol used for
this unit. This element is usually used when the relationship of this unit
to other units or units systems is unknown.</documentation>



  <complexType name="UnitDefinitionType">


      <extension base="gml:DefinitionType">


          <element ref="gml:quantityType" minOccurs="0"/>

          <element ref="gml:quantityTypeReference" minOccurs="0"/>

          <element ref="gml:catalogSymbol" minOccurs="0"/>






 UML diagram of the GML UnitDefinition class from ISO 19136:




My colleague John Hockaday is contacting the lead author of ISO 19139 to
find out why the schema and the ISO 19115 UML don't match.






Ollie Raymond
National Advice,  Maps and Standards Project

Geoscience Australia


Address: GPO Box 378, Canberra, ACT, 2601, Australia | ABN: 80 091 799 039

Ph: (02) 62499575 | Fax: (02) 62499992 | Email: Oliver.Raymond at ga.gov.au 


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