A specific registry key, ms-word: , is used to define how the system handles links to Word documents. This is particularly useful for suppressing when opening email links.
If the subkey does not exist, right-click the parent folder and select New > Key to create it manually. Ms Word Registry Key
To safely modify or create these keys, follow these steps provided by Microsoft Support : Exit all Office applications. A specific registry key, ms-word: , is used
Beyond protocol keys, Word stores user-specific data in: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word A specific registry key