Assembly: Microsoft.Office.Interop.Word (in microsoft.office.interop.word.dll)
Users who can be given permissions include individual contributors and groups of users as defined for Document Workspace sites.
The permissions you assign to ranges and selections go into effect only after a document is protected. Use the Editors collection and the Editor object to assign specific permissions to sections of a document. Then use the Protect method to protect the document.
Use the Add method of the Editors collection to give a specified user or group permission to modify a range or selection within a document.