The EcoPortal Metadata Schema is built upon the Metadata Vocabulary for Ontology Description and Publication (MOD 2.0).This comprehensive schema integrates various vocabularies, such as Dublin Core, OMV, DCAT, and VoID, and was introduced by Dutta et al. 2017.
Its primary purpose is to empower ontology developers to annotate and describe their ontologies, while also enabling ontology libraries to provide semantic descriptions of ontologies in the form of linked data.
You can take a look to the full metadata schema in the documentation (https://ontoportal.github.io/documentation/user_guide/EcoPortal).