--- a/xml.rst	Sat Jan 29 22:57:23 2011 +0200
+++ b/xml.rst	Sun Jan 30 19:25:36 2011 +0200
@@ -46,3 +46,30 @@
                 XML Media Types
   http://www.xml.com/pub/a/2004/07/21/dive.html
                 XML on the Web Has Failed
+
+* Validation of xml files.
+
+  http://infohost.nmt.edu/tcc/help/xml/lint.html
+                xmllint: A validator for XML files
+
+** Validating using the DOCTYPE.
+
+  $ xmllint --valid --noout file.xml
+
+** Validating against a specific DTD.
+
+  $ xmllint --noout --dtdvalid URL file.xml
+
+** Validating against a Relax NG schema.
+
+  $ xmllint --noout --relaxng schema.rng file.xml
+
+If your schema is in Compact Format, you can use the trang program to convert
+it to RNG format:
+
+  $ trang file.rnc file.rng
+
+** Validating against XSchema.
+
+  $ xmllint --noout --schema schema.xsd file.xml
+