The choice between an acknowledgment and a jurat is determined by what the document requires, and the document announces it. Language declaring something true under penalty of perjury is the signature of a jurat: the signer is not merely confirming that they executed the document, they are swearing to the truth of its contents, and that oath is what gives the perjury declaration its legal force. A jurat therefore requires three things an acknowledgment does not — the signer must sign in the notary's presence, must be identified by satisfactory evidence, and must take an oath or affirmation administered by the notary. An acknowledgment asks only that the signer appear, be identified, and acknowledge having executed the document, whenever it was signed. Choosing the wrong act on a perjury declaration produces a document that fails to do what it was drafted to do, which is why the notary reads the certificate wording before anything else.