The Daffodil Infoset has information about the validity status of an element. The three states of no-info, valid, not-valid are all represented.

We need to finish implementing this feature, which involves

1) representation of this information when converting infoset to XML - uses the daf:valid member - absent means no info - present is a boolean true/false.

2) construction of infoset from XML containing this daf:valid member. (Unit tests of infoset in daffodil-runtime1-unittests would use this.

3) comparison of infoset XML - this is how the TDML runner would work - as it converts the produced infoset to XML before comparing to the "known good" expected infoset as XML.