./test/VC/ElementValid6:7: element doc: validity error : Element doc content does not follow the DTD, expecting (a , b? , c+)?, got (a b)
<doc><a/><b>lacks c</b></doc>
                             ^
./test/VC/ElementValid6:8: element doc: validity error : Element doc content does not follow the DTD, Expecting more child

^