Well, what's documentation then?

Documentation
Documentation is that portion of a data collection that is required in order to re-use data. It commonly covers the subjects of sampling design, methods of data collection, questionnaire/interview design, structure of the data files, lists of variables and coding schemes, details of weighting, confidentiality and anonymisation, and provenance of any secondary data used. It also includes licence arrangements and all materials obtained through the original negotiation and data deposit, as well as post-deposit information created during preservation and ingest activities. The terms metadata and documentation are often used interchangeably and there is overlap between the two, though documentation tends to have a structure that is specific to each data collection.

UK Data Archive (2010), UK Data Archive Preservation Policy, pp.14-15