HL7 is often characterized as a "70% standard," meaning that instead of getting complete agreement from vendors, they decided to standardize most of it. (HL7 3.0 is an 80% standard, but no one really uses HL7 3.0, at least not in the U.S.)

Think of HL7 as a language with many dialects. As a result there are whole industries for translating feeds both within hospitals (integration engines) and between institutions (RHIO/HIEs).