A way of describing a formalized
Need to Know required for an EXTERNAL document. NTK requires being inside a schema
that implements ISM therefore some element in the implementing schema MUST have
ism:ISMRootNodeAttributeGroup and ism:ResourceNodeAttributeGroup since both of those
are required for a valid ISM implementation. In addition the root node of the implementing
schema must have ntk:NTKRootNodeAttributeGroup specified.