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)