HL7 specifies a number of flexible standards, guidelines, and models by which various healthcare systems can communicate with each other. Such guidelines or data standards are a set of rules that enable healthcare organizations to share and process clinical information in a uniform and consistent manner. For information about the types of HL7 standards, see http://www.hl7.org.

HL7 messaging standards version 2.x and 3.0 determine how the information is captured and communicated between two parties. These messaging standards have evolved from textual, non-XML and delimiter-based representation to XML-based syntax.