# ISO/CSDGM DCAT

## FAQ - DCAT with ISO/CSDGM

This FAQ provides a method for linking to a geospatial record (ISO/CSDGM) in [DCAT-US 1.1 metadata](https://resources.data.gov/resources/dcat-us/) for publishing into GeoPlatform.

GeoPlatform supports the publishing of [ISO 19139:2007](https://www.iso.org/standard/32557.html) and [Content Standard for Digital Geospatial Metadata (CSDGM)](https://www.fgdc.gov/metadata/csdgm-standard) metadata records. GeoPlatform can additionally support the publishing of geospatial metadata records linked within a DCAT-US record using the Distribuition and conformsTo fields. The following examples show the process for linking to geospatial records.

For more information on the GeoPlatform’s harvesting see the [Data Sources FAQ](geoplatform-data-sources.html).

## Geospatial Metadata Link Example

Data.gov [Geospatial data.json examples](https://github.com/GSA/ckanext-datajson/tree/main/ckanext/datajson/tests/datajson-samples#datajson-examples)

To link to the geospatial record add a Dataset [Distribution Field](https://resources.data.gov/resources/dcat-us/#dataset-distribution-fields) and define the [conformsTo](https://resources.data.gov/resources/dcat-us/#distribution-conformsTo) field to specify the schema for the geospatial record.

GeoPlatform supported **_conformsTo_** fields:

- `https://www.isotc211.org/2005/gmd` (for ISO 19115)
- `https://www.isotc211.org/2005/gmi` (for ISO 19115-2)
- `https://standards.iso.org/iso/19115/-3/mdb/1.0` (for ISO 19115-1)
- `https://standards.iso.org/iso/19115/-3/mdb/2.0` (for ISO 19115-1)
- `https://www.fgdc.gov/schemas/metadata` (for CSDGM)

Multiple metadata records can be linked in a single DCAT file. If an ISO 19115-3 and ISO 19115 record are both linked in the DCAT file, the ISO 19115-3 record will be used. If an ISO (19115, 19115-2, or ISO 19115-3) and CSDGM record are both linked in the DCAT file, the ISO record takes precedence and will be used.  If the DCAT file exclusively links to a CSDGM record, the CSDGM record will be utilized. 

If a **_conformsTo_** field from above is utilized, and the associated downloadURL or accessURL field does not point to an XML file, the tool will fail without further attempts to find an XML.

If a [downloadURL](https://resources.data.gov/resources/dcat-us/#distribution-downloadURL) or [accessURL](https://resources.data.gov/resources/dcat-us/#distribution-accessURL) is not present in the ISO or CSDGM [Distribution Field](https://resources.data.gov/resources/dcat-us/#dataset-distribution-fields), then the other Distribution Fields in the DCAT record will be scanned in an attempt to identify an XML file that contains a downloadURL or an accessURL. 

When the DCAT record is scanned in an attempt to identify an XML file, the following preference is used:
- The dcat:Distribution [title](https://resources.data.gov/resources/dcat-us/#distribution-title) and [description](https://resources.data.gov/resources/dcat-us/#distribution-description) fields will be scanned for the word 'metadata'. 
- The dcat:Distribution [mediaType](https://resources.data.gov/resources/dcat-us/#distribution-mediaType) field will be scanned for the following: 'text/xml', 'application/xml'.
- The dcat:Distribution [format](https://resources.data.gov/resources/dcat-us/#distribution-format) field will be scanned for the text 'XML'.

The first XML distribution file that is found will be used as the metadata file. If any of these conditions are met, and the associated downloadURL or accessURL does not point to an XML file, the tool will fail without further attempts to find an XML.

## Best practice for creating the DCAT record includes:

- Use the [downloadURL](https://resources.data.gov/resources/dcat-us/#distribution-downloadURL) field to point to the URL that provides a direct access link to the original source metadata file.
- Include a [mediaType](https://resources.data.gov/resources/dcat-us/#distribution-mediaType) and [format](https://resources.data.gov/resources/dcat-us/#distribution-format) (text/xml and XML, respectively).
- Ensure that the DCAT record title and abstract are the same as the source metadata record.
- Include the “geospatial” theme in the DCAT record so that your dataset will be marked as geospatial in Data.gov and therefore discoverable by the GeoPlatform.

### Example DCAT Snippet from “FINAL Critical Habitat for 135 plant and animal species” DCAT-US record.

Link to example [DCAT-US record](https://catalog.data.gov/harvest/object/02cf433c-55da-4f4f-8d50-d34a41e3a2f4) in Data.gov that points to an **ISO** geospatial metadata record.

```
{
    "@type": "dcat:Distribution",
    "conformsTo": "http://www.isotc211.org/2005/gmi",
    "description": "The metadata original source", "downloadURL": "https://data.doi.gov/harvest/object/212ebcce-557a-4031-9931-b21751b2d640",
    "format": "XML", "mediaType": "text/xml", "title": "Original Metadata"
}
```
### Example DCAT Snippet from “LANDFIRE Forest Canopy Cover” DCAT-US record.

Link to example [DCAT-US record](https://catalog.data.gov/harvest/object/a97404f8-442d-4f9f-949d-46c75aae5dc0) in Data.gov that points to a **CSDGM** record.

```
{
    "@type": "dcat:Distribution",
    "conformsTo": "https://www.fgdc.gov/schemas/metadata/",
    "description": "The metadata original format", "downloadURL": "https://data.usgs.gov/datacatalog/metadata/USGS.64bead9bd34e70357a31c52a.xml",
    "format": "XML", "mediaType": "text/xml", "title": "Original Metadata"
}
```

## More information

- Data.gov [Geospatial Metadata link data.json examples](https://github.com/GSA/ckanext-datajson/tree/main/ckanext/datajson/tests/datajson-samples#datajson-examples)
- Data.gov [DCAT Validator](https://dashboard.data.gov/validate)
- FAQ - [GeoPlatform Data Sources](geoplatform-data-sources.html)
- FAQ - [Baseline of GeoPlatform Standards](baseline-of-geoplatform-standards.html)
- Data.gov [DCAT-US 1.1 metadata](https://resources.data.gov/resources/dcat-us/)