An ANSI-accredited group that defines standards for the cross-platform exchange of information within a health care organization. HL7 is responsible for specifying the Level Seven OSI standards for the health industry. Some HL7 standards have been encapsulated in the X12 standards used for transmitting claim attachments, which are expected to part of the HIPAA claim attachments standard. The HL7 Claims Attachment SIG (CA-SIG) is responsible for the HL7 portion of this standard.