The RDF Data Shapes Working Group has published a Proposed Recommendation of Shapes Constraint Language (SHACL). This document defines the SHACL Shapes Constraint Language, a language for validating RDF graphs against a set of conditions. These conditions are provided as shapes and other constructs expressed in the form of an RDF graph. RDF graphs that are used in this manner are called “shapes graphs” in SHACL and the RDF graphs that are validated against a shapes graph are called “data graphs”. Such descriptions may be used for a variety of purposes beside validation, including user interface building, code generation and data integration. Comments are welcome through 6 July 2017.