Switching off validation when reading XML

Is it possible to switch off the validation of an XML file when opening it in FrameMaker?

I removed the public and system identifier from the Doctype declaration in the file (tried also removing the whole doctype declaration too) - and removed any reference to the DTD in the structured application definition. But when opening such an XML file, FrameMaker always displays a message dialog saying "Unable to validate because no DTD or Schema was specified in the XML file. Continue reading the file?". Is it possible to suppress this warning - I don't want it?

Thanks for any suggestions.