https://www.dotnetzone.gr:443/cs/blogs/abekiaris/archive/2011/01/31/xaf-pessimistic-locking.aspx  What Locking is all about Transactional isolation is usually implemented by locking whatever is accessed in a transaction. There are two different approaches to transactional locking: Pessimistic locking and optimistic locking. The disadvantageelCommunityServer 2.1 SP3 (Build: 20423.1)