A context representing a grouped commitment of information to the EHR. It is considered the unit of modification of the record, the unit of transmission in record extracts, and the unit of attestation by authorizing clinicians.

A composition represents part of a patient record originating from a single interaction between an authenticator and the record.

Unless otherwise stated all statements within a composition have the same authenticator, apply to the same patient and were recorded in a single session of use of a single application.

A composition contains organizers and entries.

The notion of a document comes particularly from the paper world, where it corresponds to the contents recorded on discrete pieces of paper. In the electronic world, a document is a kind of composition that bears resemblance to their paper world counter-parts. Documents typically are meant to be human-readable.

HL7's notion of document differs from that described in the W3C XML Recommendation, in which a document refers specifically to the contents that fall between the root element's start-tag and end-tag. Not all XML documents are HL7 documents.

A clinical document is a documentation of clinical observations and services, with the following characteristics:

1. Persistence - A clinical document continues to exist in an unaltered state, for a time period defined by local and regulatory requirements;
2. Stewardship - A clinical document is maintained by a person or organization entrusted with its care;
3. Potential for authentication - A clinical document is an assemblage of information that is intended to be legally authenticated;
4. Wholeness - Authentication of a clinical document applies to the whole and does not apply to portions of the document without the full context of the document;
5. Human readability - A clinical document is human readable.

A clinical document that conforms to Level One of the HL7 Clinical Document Architecture (CDA)