Yes, those are the EMD codes. Omega,Alpha, Bravo, Charlie, Delta, and Echo are codes for the seriousness of the call.
The first number is the page on the EMD book that the primary symptom is on. Page 9 is cardiac arrest for instance. Page 26 is a catch all (or is it 29?)
Omega - refer to another jurisdiction (Poison Control, Suicide Prevention, DCFS)
Alpha - BLS no lights/sirens. No ALS
Bravo - BLS lights/sirens. No ALS
Charlie - BLS lights/Sirens. ALS no lights/sirens
Delta - BLS and ALS lights/sirens
Echo - this is reserved for immediate death situations. This will get BLS and ALS lights and sirens, plus a close unit with a defibrilator or other life saving needs.
The last number is another part of the primary symptom. It gives a more exact description of the problem.
http://www.memphisfire.net/divisions/ems/EMD-Cards.pdf
Here is a good copy of actual EMD cards.
So, lets use page 1, Abdomial Pains for an example. Call Taker answers the phone and they go through the script on the first page of "Abdominal Pains"
Call Taker: 911, what is the telephone number you are calling from?
Caller: 555-1212
Call Taker: What is your address?
Caller: 127 Mount Evans Point. Carlock.
Call Taker: What is the emergency?
Caller: My son is complaining of stomach pains
Call Taker: Is he completely awake?
Caller: No. He was, but he isn't now.
Call Taker: I'm sending the paramedics, stay calm and I'll tell you what to do next.
Then, the call taker sends the information to the fire/rescue dispatcher as the call taker goes to another page to give instructions on determining if the patient is breathing, or if CPR is needed to be done.
On the dispatcher side, you would hear this (I'll use random units for the ambulance numbers)
"*Tone* Carlock Rescue, Carlock Ambulane. You're needed at 127 Mount Evans Point in Carlock for a 1-D-1. "
The reason for "1-D-1" is that it was the first primary symptom. The Delta response was due to the boy not being alert. The second 1 was that he wasn't alert. Some pages have multiple ones (like 9-E).
Hope that helps you out on figuring out the EMD codes.
-Dale