Thanks Dream Lands
Here is what I found on:
http://www.faa.gov/ATPubs/ATC/Chp2/atc0204.html#2-4-1
2-4-8. RADIO MESSAGE FORMAT
Use the following format for radio communications with an aircraft:
a. Sector/position on initial radio contact:
1. Identification of aircraft.
2. Identification of ATC unit.
3. Message (if any).
4. The word "over" if required.
b. Subsequent radio transmissions from the same sector/position shall use the same format, except the identification of the ATC unit may be omitted.