A digitally signed document is a locked PDF file meant for electronic submission to various institutions.
A digitally signed document from the Service Desk, University Centre, needs to be opened in Adobe Acrobat to view the digital signature. A digitally signed document that is printed out is not certified.
A hard copy of a document, which is signed and stamped in blue ink, is meant to be turned in on paper. A scan or a photocopy of a signed document is not certified.