One copy of the document (the master copy) must be unambiguously correct, so reference can be made to it if there is any dispute about the accuracy of a copy, or about an amendment that has been made.

In a paper-based system of document control, this is a hard copy, with is distinguishable from the authorised copies, perhaps because it is on a different type of paper.

Alternatively, an electronic version of a document can serve as a master copy, provided that it is appropriately protected from unauthorised alteration.

Each document, when issued or revised, must be authorised by somebody with the authority to do so.

On a hard copy, the evidence of this authorisation is usually the person’s signature.

Authorisation through a computer is also acceptable, provided that the system prevents unauthorised people from performing the authorisation.