Document endorsement requirements: include company number, unique document identifier and filing date, authenticated by registrar or digital signature. Regulation 19 requires every registered, recorded or filed document to bear the company's register number, a unique document number and the date of registration; endorsements must be signed by the Registrar with official seal or authenticated through a valid digital signature, and where endorsement cannot be entered on the document, a physical attachment with a signed note is required while electronic documents must be authenticated by digital signature.