Vale do Côa rock art as linked open data: Application profile, schemas, and data

Background: The Côa Valley Archaeological Park, a UNESCO World Heritage, preserves more than 1,200 engraved rocks spanning a long chronological sequence from Prehistory to the Contemporary period. Among these, Iron Age engravings form a significant secondary corpus with no known parallel in the Iberian Peninsula. The archaeological documentation of these engravings is stored and managed in the University of Minho's 2ArchIS database. This article presents the process of converting these previously restricted archaeological records into an openly accessible dataset, with the aim of improving data sharing, reproducibility, and future research on Iron Age rock art. Methods: The work involved transforming the 2ArchIS data into Linked Open Data (LOD). This process began with analyzing the existing data model and content. Subsequently, a series of standards-based artifacts were developed: a Dublin Core Tabular Application Profile (DCTAP), a Resource Description Framework (RDF) Schema (RDFS) vocabulary, a Simple Knowledge Organization System (SKOS) controlled vocabulary, and a Shape Expressions (ShEx) schema for data validation. The data exported from 2ArchIS was transformed into RDF using OpenRefine, validated against the ShEx schema, and finally hosted on a triplestore. Results: The project successfully generated and published a Linked Open Data dataset based on the validated Iron Age rock art records from the Vermelhosa area, together with the semantic artifacts required for future integration of additional datasets from the Côa Valley. All resulting developmental artifacts, the DCTAP, RDFS and SKOS vocabularies, and the ShEx schema, are openly available for the scientific community's use and reuse. Conclusions: This initiative has significantly broadened access to Iron Age rock art data by publishing it as Linked Open Data, thereby enhancing its potential for discovery, interoperability, and reuse. The semantic framework developed in this work also provides a foundation for the future integration of additional rock art datasets from the Côa Valley. Future efforts will include creating a user-friendly interface to help non-technical users query the triplestore.