Answered
Can someone explain the different between digitally signing a PDF document and Certifying a Document?
I understand, it is better to first Certify PDF, so multiple post signatures would not invalidate one after another, allowing multiple approvers/signers on the same document.
Signing is easy, specially using Self-signatures.
How would you certify a document, then?
A Certified PDF have some privileged rights and can execute some operations without prompting the end user, see this screengrab : http://imagesinsolites.free.fr/parkimages/certifiedPDF-1301004419359.png
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