unique id of acrobat document and tracking no. of copies of document
assign a unique id to acrobat document and when ever a document is copied or edited a new id is generated that link it to parent document. a central data base to be established by copyright owner of article.
Thanks for bringing this issue up. We do not have any plans to work on it in immediate future,we might revisit at an appropriate time in future, and would update you regarding the same.