I'm harmonizing Elevation vector data with HALE. In the INSPIRE schema for this theme there is alot of voidable attributes that I don't have information for.

I read on the INSPIRE forum that to resolve this problem the xsi:nil attribute should be set to "true" and the nilReason attribute should be provided using either of the values unkown, unpopulated or withheld.

I already gave values to nilReason attribute, however I don't know how to set xsi:nil atribute to "true".