SA Concise Oxford Dictionary: A certificate is an official document attesting or recording a particular fact or event, a level of achievement or fulfilment of a legal requirement – in JBCC® agreements only the principal agent is authorised by the employer to issue certificates of (stages of) completion and of payment due to the contractor – that are binding on the employer. If the employer disagrees with a certificate – the obligation to the contractor must be honoured, and the disagreement resolved outside the building agreement (PROCSA agreement between the client and an (principal) agent)

Note: By signing a payment certificate the principal agent binds the employer to make payment of the amount stated by the due date to the contractor = thus a payment certificate is regarded as a liquid document in law

See: 6.1; N-6.1; 5.1M; 5.0P; -5.0 N; 4.0M; 4.1P; 4.1N; 3.1M