title: Why it can be bad to have a not-valid XSD?
body: <p>I have a set of XSD files in my project. I tried to validate them using the code, suggested in this question:</p>
  
  <p><a href="https://stackoverflow.com/questions/16519435/validating-xsd-itself">Validating XSD itself</a></p>
  
  <p>It turned out, that some of my XSD files are not valid.</p>
  
  <p>This doesn't prevent me from validating some XML with this not-valid XSD files. So in which situations that can really matter? </p>