We are pleased to announce version 1 of the Linked Places (LP) format, to be used for contributions to World-Historical Gazetteer (WHG) and to the Pelagios “registry index” that underlies its Recogito annotation tool and Peripleo search interface. We were joined in this effort by Rainer Simon of Pelagios and Graham Klyne and Arno Bosse of Oxford’s Cultures of Knowledge, so a big shout of thanks to all three.
A basic specification of the format has been published to GitHub, along with some relevant files:
- a relatively complex sample record;
- the JSON-LD context file it references;
- a simpler sample record;
- a serialization of the larger sample record to N-QUAD format, demonstrating RDF compatibility;
- our first external contribution of ~13,000 records from Werner Stangl’s HGIS de las Indias
The spatial footprint of the HGIS de las Indias contribution appears in Figure 1; more about that data and ongoing efforts to make it the “seed” for a virtual LatAm Gazetteer within WHG are forthcoming soon.
An Interconnection Format, Not “The One” Model
Historical research projects producing gazetteer data have distinctive data models reflecting their source data and project-specific requirements. We are completely agnostic as to contributors’ internal models and formats. The Linked Places format provides a uniform way to build links between different gazetteers.
WHG and Pelagios are aggregating contributions which have great variety in scope and granularity. With LP format, we are striking a balance between accommodating detail and offering simplicity. Two underlying conceptual models: of Place and of attestations. We say (hopefully not controversially) that places have, over time,
- one or more names in various languages
- one or more functional types
- zero or more known spatial footprints (geometries)
- one or more relations to other places
Gazetteer data developers gather attestations of these properties, often temporally scoped. That is, names, types, geometries, and relations were/are true for some timespan—whether we have that detail to hand or not. Thing is, some projects do and some don’t, and we must accommodate both cases.
The simple subject, predicate, object form of RDF is not adequate for these kinds of relations and so we have reified them as attestations: NameAttestation, TypeAttestation, Setting, and RelAttestation. Each can be temporally scoped with a “when” element and include citation information, although this is not required. We also permit (and encourage) a global “when” element for the record—effectively the union of temporal attributes for names, types, geometries, and relations.
We ask that all contributions include, if at all possible, at least one closeMatch or exactMatch relation to a published place record having a de-referenceable URI. These links are “coin of the realm” so to speak. If an incoming record shares such a link with an existing record in our registry index, we add it to the existing record. If it shares no such link with any existing records and doesn’t otherwise match name, type, and geometry, a new registry index record will be created using it as a seed.
Three other kinds of LinkAttestations to existing web resources are recognized: subjectOf, primaryTopicOf, and seeAlso.
Several “record-level” properties round out this format, as detailed in the GitHub specification: title, ccode (modern country), description(s), and depiction(s).
Please get in touch if you are interested in contributing to WHG. The Linked Places format is not set in stone; this v1 is subject to revision based on our experiences ingesting contributions. The ingest of HGIS de las Indias data as a gazetteer offered to users of Recogito has succeeded, following significant manual effort to make the transformation from that project’s complex model to LP format. Temporally scoped namings and parthood relations in that dataset made it over, but are not reflected in Recogito. Simpler example datasets will be added soon. The WHG web interface and API are being designed to expose all contributed place attributes, but they won’t be available for several months.
Linked Places Annotations
Next up in our format-creation effort is an update to the standard format for contributions of annotations. Just as Peripleo displays coins and inscriptions associated with places in its registry index, the WHG graphical search will such annotation records, but in our case for historical routes, datasets, and bibliographic records. The format previously used by Pelagios/Peripleo will be updated soon—details to follow.