The ontology provides a FAIR, interoperable vocabulary for grammatical error annotation and correction, integrating the English-focused ERRANT taxonomy with Czech-specific extensions from ERRANT-CZ and fine-grained categories derived from Czech proofreading and correction rules (Opravidlo). The ontology formalizes error types, subtypes, and correction operations in RDF, aligns linguistic properties with the LexInfo ontology, and supports multilingual grammatical error correction research, annotation interoperability, and data reuse.