MDG_Spec1
1. Introduction
The Part 1 is available at http://wis.wmo.int/WCMPpart1.
The structure of the document is as follows:
- Scope
- Conformance
- Normative References
- Terms and Definitions
- Symbols and Abbreviated Terms
- XML Encoding
- Declaring Compliance with WMO Core Metadata Profile
- Metadata Uniqueness and Discovery within WIS DAR Catalogue (SRU Mapping)
- Description of Data for Globale Exchange within WIS
- Summary of Additional Restrictions
- Amendments to Code Lists / new CodeList
- WMO Core Metadata Profile UML Model
Sections 6, 8, and 9 defines the requirements of WMO Core Metadata Profile (WCMP) in addition to ISO 19115 and 19139.
2. Requirements
Requirements are basically mandatory, as indicated by the verb "shall". Some requirements applies for only limited metadata records. That is called conditional, and the condition is indicated by italic letter in this page.
2.1. XML Encoding (Section 6)
ISO 19139
6.1.1 Each WIS Discovery Metadata record shall validate without error against the XML schemas defined in ISO/TS 19139:2007.
ISO provides XML schemas for ISO/TS19139:2007 in the W3C XML Schema language. See MDG_Schema for more detail.
ISO 19115 Annex A
6.1.2 Each WIS Discovery Metadata record shall validate without error against the rule-based constraints listed in ISO/TS 19139:2007 Annex A (Table A.1).
ISO provides only verbal description of requirements, but they are implemented as Schematron. See MDG_Schema for more detail.
Default Namespace
6.2.1 Each WIS Discovery Metadata record shall explicitly name all namespaces used within the record; use of default namespaces is prohibited.
The default namespace declaration looks like
xmlns="http://www.isotc211.org/2005/gmd", by which we could use <MD_Metadata> tag instead of <gmd:MD_Metadata>. But unfortunately some implementations had trouble with it.GML Namespace
6.3.1 Each WIS Discovery Metadata record shall declare the following XML namespace for GML: "http://www.opengis.net/gml/3.2" .
Some old implementations and documents use
"http://www.opengis.net/gml/" instead, but this is treated as totally different thing in XML processing.2.2. General Requrements (Section 8)
Unique metadata identifier
8.1.1 Each WIS Discovery Metadata record shall include one
gmd:MD_Metadata/gmd:fileIdentifier attribute.8.1.2 The
gmd:MD_Metadata/gmd:fileIdentifier attribute for each WIS Discovery Metadata shall be unique within the WIS.WIS has a convention to avoid collision of identifiers generated by different organizations. See MDG_MdMgt for details. See also MDG_Spec1 below for a specific regulation applies to globally-distributed data (such as GTS data).
WMO_CategoryCode keyword
8.2.1 Each WIS Discovery Metadata record shall include at least one keyword from the WMO_CategoryCode code list.
8.2.2 Keywords from WMO_CategoryCode code list shall be defined as keyword type "theme".
Grouping of Keyword by Thesaurus
8.2.3 All keywords sourced from a particular keyword thesaurus shall be grouped into a single instance of the MD_Keyword class.
Bounding box
8.2.4 Each WIS Discovery Metadata record describing geographic data shall include the description of at least one geographic bounding box defining the spatial extent of the data.
2.3. Requirements for globally-distributed data (Section 9)
Distribution scope
9.1.1 A WIS Discovery Metadata record describing data for global exchange via the WIS shall indicate the scope of distribution using the keyword "GlobalExchange" of type "dataCentre" from thesaurus WMO_DistributionScopeCode.
Metadata identifier
9.2.1 A WIS Discovery Metadata record describing data for global exchange via the WIS shall have a
gmd:MD_Metadata/gmd:fileIdentifier attribute formatted as follows (where {uid} is a unique identifier derived from the GTS bulletin or file name): urn:x-wmo:md:int.wmo.wis::{uid} .Data policy
9.3.1 A WIS Discovery Metadata record describing data for global exchange via the WIS shall indicate the WMO Data License as Legal Constraint (type: "otherConstraints") using one and only one term from the WMO_DataLicenseCode code list.
9.3.2 A WIS Discovery Metadata record describing data for global exchange via the WIS shall indicate the GTS Priority as Legal Constraint (type: "otherConstraints") using one and only one term from the WMO_GTSProductCategoryCode code list.
3. Recommendations
The document also contains some recommendations.