CBS-Ext.(06) agreed version 1.0 of the WMO Core Profile of the ISO Metadata Standard.

This document presents the extensions to the ISO Metadata Standard.

A number of extension points were identified:

The WMO community need to resolve creation / issue / publication times with a granularity finer than 1 day. Therefore, CI_Date is deemed insufficient.

However, CI_Date (from ISO 19115) is realised as gco:Date_PropertyType (from ISO 19139). gco:Date_PropertyType is implemented as a CHOICE between gco:Date and gco:DateTime, thus delivering the functionality required within the WMO community.

There is no need to extend CI_Date.

The WMO community employ numerous 'controlled vocabularies' to restrict the set of values used to describe information. Previously, it had been thought that it would be necessary to create 'Code Lists' (as described within ISO 19115 geographic information - metadata, clause B.5 Codelists and enumerations).

However, further analysis suggests that the MD_Keyword element can be used to reference external controlled vocabularies via the MD_Keyword.thesaurusName attribute.

The recommendation is that artifacts such as WMO volume WMO-No. 182 International Meteorology Vocabulary and WMO volume WMO-No. 49 Technical Regualtions be implemented as as Multilingual CodeList catalogues (CT_CodelistCatalogue, from ISO 19139 geographic information - metadata (XML schema implementation), clause 7.4.4.4) which are cited via MD_Keyword.thesaurusName.

The proposed WMO_CommunityTopicCategoryCode, enabling fine-grained thematic description within the meteorological domain (weather observations, weather forecasts, meteorology, hydrology, climatology etc.), can also be implemented in this way: only a standard MD_Keyword element need be used rather than an employ a metadata extension.

The WMO Community express the need to use 'hierarchical' keyword taxonomies - such as NASA's GCMD Science Keywords [http://gcmd.nasa.gov/Resources/valids//gcmd_parameters.html] - in order to describe geographic information.

To achieve this, the standard CharacterString element has been extended to add a delimiter (token) between 'levels' in the hierarchy.

The delimiter can be specified at the instance document level, but has default value = "|".

Example:

XML serialisation:

Within the WMO community, ANALYSIS TIME is often used to differentiate between datasets from numerical simulations.

The analysis time is considered to be a time instant.

This extension provides an analysisTime attribute that can be used to identify a particular dataset.

Within the WMO community information atrifacts (particularly weather forecasts) are perishable; that is they are only valid for a fixed period of time after issue as another, potentially more accurate forecast is likely to have been issued.

In particular, aviation weather forecasts are valid for only a specific period as defined by the Internation Civil Aviation Authority (ICAO)

This extension enables one to specify the time period during which the dataset is valid. Outside this time period, the dataset must not be used for operational purposes.

UML is the canonical notation used in the ISO 19100 series of standards for Geographic Information developed by ISO/TC 211. However, UML provides a rich palette, and even within class- diagrams the UML elements may be combined in a variety of ways to represent similar functions. In order to restrict the variability, a strict "profile" of UML is used. This is defined primarily in ISO 19103, with some contextual clarification in ISO 19109, 19118 and 19136.

"WMO Core Metadata Profile - Extensions" builds on the "HollowWorld" model developed within the SEEGrid community.

The primary resource is the "WMO Core Metadata Profile - Extensions.EAP" file, which is a UML template in "Enterprise Architect" format.

Enterprise Architect is a UML modelling interface from Sparx Systems http://www.sparxsystems.com.au.

A "read only" version of the software is available at no cost from http://www.sparxsystems.com.au/products/ea_downloads.html

The base "HollowWorldOM.EAP" (without WMO extensions) can be found here: https://www.seegrid.csiro.au/subversion/xmml/HollowWorld/

+++++

The WMO Core Profile Metadata Extensions can be found by browsing the 'Project View':

Model > HollowWorld > WMO Core Metadata Profile

A discussion concerning the application of HollowWorld can be found at the following link:

Model documentation (exported from Enterprise Architect) can be found at the following links; either as RTF or HTML

The XML Metadata Interchange format allows a model from one tool to be exported (as XMI) and imported into another tool.

[Refer to wikipedia for more information: http://en.wikipedia.org/wiki/XMI]

"wmo_metadata_extensions.xmi" has been exported from "Enterprise Architect" UML modelling tool via the "XML Model Interchange" format; UML 1.3, XMI 1.0.

The model provided here is ONLY the WMO extensions to ISO19139. For a complete model (into which the WMO extensions can be imported) refer to https://www.seegrid.csiro.au/subversion/xmml/HollowWorld/

The extensions illustrated within the UML model have been serialized to W3C XML schema.

The serialisation is (believed to be) compliant with ISO 19139 'geographic information - metadata (xml schema implementation)' clause 8 'ecoding rules' and clause A.3 'conformance requirements - extensions'.

Codelists etc.

All example XML instances have been validated (as provided) with oXygen 7.2 XML editor [http://www.oxygenxml.com].

Note that external schema are referenced at source (i.e. http://www.isotc211.org/2005). The WMO extensions schema is referenced locally (../wmo/wmo_metadata_extensions.xsd) as it is yet to be published externally.

oXygen uses the java Xerces XML Parser from apache.

Due to issues regarding the 'clash' between GML 3.1.1 and ISO19139 (schema packages seem to be imported multiple times) the 'honour-all-schemaLocations' was turned OFF [Options > XML Parser > XML Parser Features > http://apache.org/xml/features/honour-all-schemaLocations]

For more details on Xerces, refer to:

The 'honour-all-schemaLocations' feature is discussed at:

Vector Smart Map level 0 (VMAP0); from ISO 19139 'geographic information - metadata (xml schema implementation)' clause D.3

The examples included here are acknowledged as being incomplete.

The subject 'domain' of the examples are aviation forecasts: Terminal Aerodrome Forcasts (TAFs) as currently exchanged on the GTS.

The TAFs used within the examples are described in the following document:

The extensions are now packaged within a single XML schema document (wmo_metadata_extensions.xsd) for simplicity.

WMO_DelimitedString:

Attribute delimiter:

WMO_SimulationDataIdentification:

WMO_UsagePeriodConstraints: