As I open the DDOC file, I am informed of the old file format. What does it mean?
From the ID software version 3.12 it is no longer possible to create DDOC containers in the DigiDoc3 Client. It is also not possible to add/remove signatures to/from the container signed in the in the DDOC format.
Upon opening a file in the DDOC format, the users gets the following notification message: The current file is a DigiDoc container tha tis not supported officially any longer. You are not allowed to add or remove signatures to this container.
After you've clicked on "OK", you will see the DDOC container content and signatures displayed.
If you click on the "Sign" button, the respective messages informing you of the old format is displayed once again:
To view the DDOC container content and signatures, click on the "Cancel" button.
If you need to give your signature to DDOC file, then be advised to contact the document creator and let him/her to create new digitally signed document in BDOC format.
If it is impossible, then create new BDOC file and add DDOC container into it and sign it digitally. Instructions for that can be found from here (in Estonian).