What is the difference between Place Signature, Sign Document and Certify in PDF?
What is the difference between "Place Signature", "Sign Document", and "Certify" in the PDF format? These operations appear to achieve the same result.
The Place Signature function is used to place signed digital signature fields in documents, whereas the Sign Document function is used to sign existing signature fields. These are also sometimes referred to as "approval signatures" and multiple can exist at any time in a file.
Sign Document will operate in the same manner as Place Signature unless the document contains more than one unsigned digital signature field, in which case it will prompt the user to select the digital signature field they wish to sign. Likewise, these are also "approval signatures".
Certify, or Certify (Invisible), are defined by the PDF specification as a special type of signature (a "certify signature") of which only one can exist in the document at a given time. This should generally be placed as the last signature in a document, or in files which no other signatures need to be placed.