new（Nu）HTML5 Validator 具有各种预设的RELAX NG模式，包括XHTML5

The new (Nu) HTML5 Validator has RELAX NG schema for various presets including XHTML5

参见 https://bitbucket.org/validator/syntax/src/ed90a83ab0fd/relaxng https://github.com/validator/validator/tree/master/syntax/relaxng

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