Description of the illustration doc_hierarchy.gif
The image shows the document protocol hierarchy. The top level consists of the document protocol (HL7 in this example). The second level consists of the document protocol version (HL7 V2.3.1 in this example). The third level consists of the document type (ACK_A01 in this example). The fourth level (bottom of the hierarchy) consists of the document definition (the XSD file and associated information in this example).