ShEx 2.1 defines shapes and node constraints for describing RDF graph structure
Final Community Group Report (8 Oct 2019) for Shape Expressions Language 2.1: RDF node and graph structure descriptions for validation and interfaces.
Shape Expressions (ShEx) describe RDF nodes and graph structures: node constraints on IRIs, blank nodes, or literals, and shapes over triples with predicates, cardinalities, and datatypes. Shapes can communicate structures for processes or interfaces, generate or validate data, or drive user interfaces. ShEx 2.1 adds IMPORTS and language tag value sets.
Based on: Shape Expressions Language 2.1 · W3C Shape Expressions Community Group / shex.io