I was looking for an option to add the 'Draft Item Security' in the list schema file. This can be changed in the UI when you click the document library settings -> versioning settings. The possible options of 'Who should see draft items in this document library?' are:

• Any user who can read items (DEFAULT)
• Only users who can edit items
• Only users who can approve items (and the author of the item)

If you want this setting automatically in you document library, you must add the DraftVersionVisibility attribute to your List node in the schema.xml. The value must be an integer which has the next options:

• 1 = Only users who can edit items
• 2 = Only users who can approve items (and the author of the item)

• All other values = Any user who can read items (DEFAULT)

So for example :

Have fun!