https://xmlschemata.org/relaxng-modern-schema-validation/
XML Schema Validation: From RelaxNG to Modern JSON-LD
Apr 29, 2026 - How XML schema validation evolved from DTD and RelaxNG into modern JSON-LD and Schema.org structured data. Validate today with the free schema validator.
xml schemavalidationrelaxngmodernjson
https://ruby-doc.org/3.1.4/gems/rexml/REXML/Validation/RelaxNG.html
class REXML::Validation::RelaxNG - rexml: Ruby Standard Library Documentation
standard libraryclassvalidationrelaxngruby