An sdo file extension is related to the Signere.no a digital signature software.
SDO file extension - Signere.no signed document
What is sdo file? How to open sdo files?
File type specification:
The sdo file extension is associated with the Signere.no, a digital signature software for Microsoft Windows that allows users to protect their case sensitive documents.
The sdo file stores signed and protected document.
This sdo file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.