It is the alias. You see "FROM NmsRecipient R0" in the second line. The system is creating an alias for the table, NmsRecipient. It is a best practice to alias data sources but also helps to clarify a field name that may exist in multiple data sources being queried. It is the same as saying NmsRecipient.FirstName, NmsRecipient.LastName, etc...
I do believe that ACM will always alias tables. it would not always be R0. Especially when there are more than 1 table involved.