The B-12 IHO Guidance to Crowdsourced Bathymetry specifies a metadata associated with each data file, but provides only limited advice and examples on how to encode B-12 metadata and data in the expected JSON format. The CSBSchema project provides schema documents in the JSONSchema format to allow B-12 JSON metadata and data (when stored in GeoJSON format) to be validated, and maintains separate schemas for different dialects of B-12 version 3 (including proposals for the next version).  The project also includes software to validate files against a specific schema.