A Delta is a collection of one or more DeltaChanges, each of which contain information about a change made to the table. A delta change has properties that you can access to get further information about the change. For instance there is a property to indicate the type of change, the original value before the change occurred, the new value of the field, the status of the change before and after it has been processed by the server.
In addition, delta changes also have a Message property that you can set to custom text, after a change is processed, and if the server encounters a problem applying the change it will be filled with the error message.
You can access the old and new values either by field name or by index. When you access them by index, keep in mind that the index of fields might not be the same as in the original data table, as only fields whose LogChanges property was set to true in the original schema are included in these arrays.