While 15.51 is a minor maintenance release, it includes a fair number of corrections as well as an update to the database engine. The full list of changes made to Atrex 15.51 is available at http://atrex.com/atrexchangehistory.asp.
If you are running a client/server configuration, it is recommended that you update the server engine as well. This is required If you are upgrading from a version earlier than Atrex 15.03.
If updating your installation from a version earlier than 15.50, please run the "Options - Batch Processing" function once from within Atrex with the Verify Database Structure option selected.