When a document requiring notarization contains  acknowledgment wording  the signer is not swearing or affirming to the truthfulness of a document, the signer is simply acknowledging that they signed the document. Acknowledgments are used to verify the identity of the signer and confirm that they indeed signed a document requiring notarization. For example in California when an acknowledgment is presented on a document requiring notarization the signer is not required to sign the document in the presence of the Notary Public ( document may be pre signed) however the signer is required to personally appear in front of the Notary Public to verbally confirm their signature in person.