// must have no more than one of VAR and VAR_DOM ...
if (Util.isSpecified(us, VAR) && Util.isSpecified(us, VAR_DOM))
return false;
// ... and must have no less than one of VAR and VAR_DOM
if (!(Util.isSpecified(us, VAR) || Util.isSpecified(us, VAR_DOM)))
return false;
// When either 'scope' is specified, its 'var' must be specified
if (Util.isSpecified(us, SCOPE) && !Util.isSpecified(us, VAR))
return false;
if (Util.isSpecified(us, SCOPE_DOM) && !Util.isSpecified(us, VAR_DOM))
return false;
return true;