X-12 An American National Standards Institute (ANSI)-accredited group that defines EDI standards for many American industries, including health care insurance. Most of the electronic transaction standards mandated or proposed under HIPAA are X12 standards. Related Terms: Data Interchange Standards Association; Draft Standard for Trial Use ; Electronic Data Interchange; HIPAA Data Dictionary ; Health Care Code Maintenance Committee; Health Care Provider Taxonomy Committee; NUBC EDI Technical Advisory Group ; United Nations Rules for Electronic Data Interchange for Administration, Commerce, and Transport ; Washington Publishing Company ;