Information becomes insecure and vulnerable in the absence of a reliable and straightforward method of document identification. In the event a document is misappropriated or misused, the consequences can be minor or catastrophic. Remember, most all PDFs originated from an unprotected Word document.
Unattended and unlabeled documents are an all to common event in daily business. We print documents for many of reasons -- frequently without any form of label to reflect our intent to prevent misuse. Employing a rubber stamp in the margins of a document is a waste of time in ineffective.
The most efficient method of dealing with paper and PDF document management is to identify and label the document at the time it is printed. In the case of a PDF, the document marking should be done at the time it is created from Word. This requires both a method that is easily implemented and a policy requiring the action. If the PDF is not labeled or identified when it is created from Word, it requires a manual use manipulation and a PDF editing program to mark or stamp the document. Moreover, if the user wants to mark only selected pages of the PDF, each must be done individually which can be a tedious process.
As to the method, the document identification process must be thorough and capable of marking all the documents' pages with appropriate and/or necessary indicia that is unalterable. The method must also be able to accept user-input to ensure that the marking is wholly appropriate for the document and handle extraordinary situations where truly custom stamps or legends are required.
While a stamp in the margin is better than no stamp at all, it doesn't make much of an improvement over the antiquated rubber stamp. In order to be effective, the method must be automated. And the method must be capable of combining the text and the indicia in such a manner that it cannot be removed. User-friendliness is of paramount importance. If the use of the product requires data entry or command-line use, it is not likely to be used in an effective manner.
Visible watermarks, while good for intra-office work and controlled-print environments, are not the most secure form of document identification. The visible watermark, if in shaded gray, can be almost instantly removed by a contrast setting on any number of copy machines with that setting. Color watermarks are a little more secure method, but still are subject to removal in a similar manner.
Document marking that is embedded in the body/text of a document is the most reliable. This form of marking is where the indicia is the same color as the body text which prevents the removal-by-copier scenario. Under this condition there is no marking that can be covered or 'contrasted' out of the document. This method provides the most paper document security in an document management program.