This policy setting controls how Word opens a file for editing on document management servers that support co-authoring. ...

This policy setting controls how Word opens a file for editing on document management servers that support co-authoring.

If you enable this policy setting, Word will prevent co-authoring by taking an exclusive file lock. 

If you disable or do not configure this policy setting, Word will allow co-authoring by taking short-term shared locks. 

Note: When file synchronization via SOAP over HTTP is turned off it will prevent co-authoring.