hello, hope this helps You, I asked a guy who done the theatrical mix for Waterworld and he wrote this:

"When we mix for a film, we mix in a discrete mode, that being, we monitor without the Dolby or DTS matrix inserted into the monitors. For "Waterworld" we created a 5.1 mix for four formats: Dolby Digital, DTS, and SDDS and the 2 trk LT RT . I have no idea what happens once the project leaves for DVD mastering. It's done somewhere else, and sometimes not even on the studio lot. It's possible that the DVD made into a 5.0 was generated from the 2 trk Print Master."