Adobe ACROBAT READER 7.0 Manual page 126

About approval workflows
Acrobat 7.0 can send PDF documents as email attachments for others to approve and
return to the initiator. If Acrobat 7.0 Professional is used to initiate an approval workflow,
the PDF document may include additional usage rights that allow Adobe Reader users to
participate. You can apply approval stamps and commenting tools to PDF documents that
have commenting enabled. (See About Adobe PDF documents with additional usage
rights.)
When participants receive an approval request, they can approve the PDF document by
adding a stamp and then send it to the next approver, or they can return the document to
the initiator without approval. Participants use a digital identity stamp to indicate their
approval. (See Using digital identity stamps.) The workflow ends when the final approver
returns the PDF document to the initiator. If a document is not approved, the approval
workflow must be reinitiated. Approval workflows are suitable for projects or documents
that require approval at various levels of an organization.