GEMINI and ISO 19139 metadata
The CSW/WAF/Single-File harvesters all require the records to be in either GEMINI or ISO 19139 format, depending on whether the data is (geo-)spatial or not:
- ISO 19139 for non-spatial data
- GEMINI 2.3 for spatial data (including INSPIRE datasets)
You should ensure that ISO 19139 non-spatial data has a resource type of “nonGeographicDataset”, as follows:
<gmd:hierarchyLevel> <gmd:MD_ScopeCode codeList="http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_19139_Schemas/resources/codelist/gmxCodelists.xml#MD_ScopeCode" codeListValue="nonGeographicDataset"> nonGeographicDataset </gmd:MD_ScopeCode> </gmd:hierarchyLevel>
Otherwise it will be treated as GEMINI spatial data and you’ll get see GEMINI validation errors.
ISO 19139 is an XML schema for the “Geographic Metadata (gmd)” specification “ISO 19115”. You can purchase ISO 19139 as a PDF from ISO: ISO/TS 19139:2007. It is fine though to simply refer to the ISO19139 XSD schema.
When harvested, ISO 19139 records will be validated using two schemas:
- ISO19139 XSD Schema (EDEN 2009-03-16) (gmx/gmx.xsd)
- ISO19139 Table A.1 Constraints Schematron (Medin/Parslow 1.4)
Note: since ISO 19139 is designed for spatial data, it might seem anachronistic to use it for non-spatial data. However it is sometimes useful when using a Geographic Information System to also store both spatial datasets plus a few non-spatial datasets in the same system.
GEMINI is the UK standard for spatial metadata. It is based on ISO 19139 and takes into account the needs of INSPIRE too.
There are two key differences with GEMINI (compared to ISO 19139):
- the resource type will be ‘dataset’, ‘series’ or ‘service’ (not ‘nonGeographicDataset’)
- the spatial extent of the data is indicated using a Geographic Bounding Box
Detailed guidance on GEMINI is provided: UK GEMINI Encoding Guidance
ISO 19139 and GEMINI2 are similar, but it is suggested you validate using the GEMINI2 schematron in your GIS before publishing to data.gov.uk, to spot any issues earlier in the chain.
When harvested, GEMINI records will be validated firstly with the two ISO19139 schemas and then finally with the GEMINI schematron: