Distinguish Author signature from approval signature

Hello, how can I distinguish a Author signature from a signature of approval, using pdfnet code?
You have a code example?
Thank you.

You can distinguish between the two by the presence of a DocMDP dictionary (https://groups.google.com/d/msg/pdfnet-sdk/yNbgF7Ds5ZI/jOb5xiRFDQAJ). The code would look similar to the snippet posted to https://groups.google.com/d/msg/pdfnet-sdk/Oy0DWhdlYPU/cxZUsv5PT14J, but looking for the DocMDP entry in the dict, alongside the ByteRange entry.