Overview Code Lists
Adoption of common code lists is an important aspect of data harmonization. For INSPIRE the INSPIRE registry is the source of common code lists. Other common codelists relevant to the soil domain are available in FAO Agrovoc, GEMET, OGC definition server, ISO TC211, and GLosis. At a national level some countries have implemented a national repository for common national codelists which may be relevant (either as a source or as a target, to publish an extended list).
Adoption of common code lists is an aspect of step 4) data organization in the soil information workflow, although it could also impact step 1) data collection.
The adoption of code lists has three aspects:
- Inventarisation of the code lists used in the source model
- Evaluation of the differences between local and common code lists
- Some code lists are a full match
- Some code lists need to be extended, or values mapped
- Some local code lists do not (yet) have a common code list available
- In cases where the common code list cannot (fully) be adopted, the code list needs to be published in a local repository
Adoption of a dedicated codelist is relevant for example for Soil classification. Many of the national soil classification systems have much more detail than the World Reference Base, as suggested to be used by the TG Soil.
| Please note that the harmonization meant here is harmonization of the description of the data, for example describing a soil observation of pH KCl with dilution 1:10 in the same way across Europe. The harmonization of the data itself, for example transforming pH KCl values to pH H2O values, is a separate step and not described in this wiki. More information on that harmonization can be found in D6.1 chapter 3.5 page 122. |
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The soil theme has a large number of code lists, ranging from soil type to ranges of grain size. Many code lists originate from the FAO soil classification and are published in the INSPIRE registry.
If you missed the 2022 EJP Training on Soil data good practices, you can still have a look at a presentation about codelists.
Implementation options for managing and publishing a code list:
Minimal
The most basic form of publishing an alternative or extended code list is to place a code list file on a web location and reference values in it as https://example.org/codelist.xml#concept (see for example http://schemas.opengis.net/iso/19139/20070417/resources/Codelist/gmxCodelists.xml)
| Cookbook | Software | Description |
|---|---|---|
| Code list as iso19135 | Publish an XML file on a web location |
Traditional
Extended code lists can be published in a local or national instance of the Re3gistry software. This open source project is hosted by JRC to facilitate the INSPIRE registry.
| Cookbook | Software | Description |
|---|---|---|
| Code list in Re3gistry | Re3gistry | Publish a codelist in Re3gistry |
Experimental
A standard for the definition of code lists is Simple Knowledge Organization System (SKOS). Any SPARQL endpoint can be used to publish a code list based on SKOS. Software exists which facilitates the consumption of SKOS data from a SPARQL endpoint in a human friendly way. An example is Skosmos.
A powerfull aspect of SKOS is that you can link from a concept to existing concepts in other codelists using link relations such as: sameAs, Broader, Narrower.
| Cookbook | Software | Description |
|---|---|---|
| Extend a codelist | How to extend an INSPIRE codelist | |
| Publish a SKOS codelist | Virtuoso Skosmos | Publish a code list in semantic web |
| GRLC.io | GRLC.io | A conveniance API on top of your SPARQL endpoint |