How to fix Eclipse validation error “No grammar constraints detected for the document”?

Question

Eclipse 3.5.2 is throwing an XML schema warning message:

No grammar constraints (DTD or XML schema) detected for the document.

The applica

Answer 1

What worked for me is to right click the xml-file in the tree (usually on the left hand side in eclipse) and clicked the validate. Since then, the warning never came back.