The Nullification Document is designed to be used by CDA domains. It provides functionality for marking documents as nullified (withdrawn). Note: This message definition represents the conformance model and schema which detail the various constraints on the balloted CDA R2 model. Instances which flow between systems should be built to the "on-the-wire" CDA model and schema as contained in the "Generic CDA" pack under the "Associated Specifications" tab (above). The "on-the-wire" instance must must comply to the contraints detailed within this section. For further information about this process see Technical Guidance for Implementation of Templated CDA Domains also under the "Associated Specifications" tab (above).