Server Configuration > Server Policies for SCM > Locks Policies > Setting Locking Policy for Text
  
Setting Locking Policy for Text
The locking policy determines the type of locking model you are using in your development environment. You set the locking policy for text files. The check out and lock commands attempt to obtain this type of lock by default. For each type of file, you can select one of the following settings:
Exclusive
This locking policy supports a strict locking model. An exclusive lock must be obtained before a member can be checked in. A non-exclusive lock can be obtained, but it must be upgraded to an exclusive lock before a member can be checked in. The check out and lock commands attempt to obtain an exclusive lock by default. If an exclusive lock cannot be obtained because another user has an exclusive lock, these commands obtain a non-exclusive lock.
* 
Exclusive locking is recommended for text files that are not easily merged.
Non Exclusive
This locking policy supports the advisory locking model. Either a non-exclusive lock or an exclusive lock must be obtained before a member can be checked in. The check out and lock commands attempt to obtain a non-exclusive lock by default.
If a member is locked with both an exclusive and a non-exclusive lock, the exclusive lock takes priority. The user with the non-exclusive lock must wait for the user with the exclusive lock to check in the member first.
None
This locking policy supports an optimistic locking model. No lock is required before a member can be checked in: either type of lock may be obtained but is not mandatory. The check out does not obtain a lock by default.