TOPIC:

Hello Radaee. There was a problem after saving the document. If you compare the original document and the document after saving by content, then unknown data appears that interfere with further actions on EDS(Electronic Digital Signature), because the documents are not the same. The document changes even when I don't change (save) anything in the annotations - annot.SetName (data)); ), the changes happen after document.Save() fires. Is there anything you can do about this so that the document doesn't change after document.Save ()? Thanks.

It's normal behaviour that different PDF engines handle inner files' tree differently.
If you've a signed document you should save it because any save will change nodes ids and low level metadatas.

Is there any reason why need to invoke the Save() even when any change is applied to the document?
 

Thanks for the answer. Then one more question: is it necessary to call document.Save() after the current how do we change the data (content) of the annotations of this document?

Your case is more clear now.

To store annotations you shall Save().
Saving annotations you're altering the PDF file and the signature is invalided.

No way to alter the PDF structure maintaining the signature valid.