RELAX NG validation is supported natively in some editing
environments, such as <oXygen/> (see Figure 3-1),
XMLmind, and Emacs (with
nxml-mode). <oXygen/> and XMLmind also support Schematron validation. There are also several
standalone validators—for example, Jing and Sun’s Multi-Schema Validator
If your documents make use of several namespaces (e.g., SVG and MathML embedded in DocBook), tools that support NVDL, Namespace-based Validation Dispatching Language [NVDL], can greatly simplify complex validation scenarios.
Figure 3-1. <oXygen/> XML Editor validation