Validates the given file against the appropriate VOTable schema.
filename : str
The path to the XML file to validate
version : str
The VOTABLE version to check, which must be a string “1.0”, “1.1”, or “1.2”. For version “1.0”, it is checked against a DTD, since that version did not have an XML Schema.
The VOTABLE version to check, which must be a string “1.0”, “1.1”, or “1.2”.
For version “1.0”, it is checked against a DTD, since that version did not have an XML Schema.
returncode, stdout, stderr : int, str, str
Returns the returncode from xmllint and the stdout and stderr as strings