Walkie-talkie code for 'understood' or 'okay'—universal acknowledgment on film sets that a message was received.
What does 10-4 mean?
10-4 is the universal walkie-talkie code for "Understood" or "Okay." It confirms that a message has been received and understood – the most important acknowledgment in radio communication on set.
Usage
| Situation | Response |
|---|---|
| Instruction received | "10-4" |
| Information understood | "10-4, thank you" |
| Agreement | "10-4, will do" |
| Confirmation | "10-4, en route" |
Alternatives
| Term | Meaning | Origin |
|---|---|---|
| 10-4 | Understood | CB Radio |
| Copy | Understood | Military |
| Roger | Understood | Aviation |
| Copy that | Understood | Military |
| Affirmative | Yes/Understood | Military |
Why is it important?
| Reason | Description |
|---|---|
| Confirmation | Sender knows: Message received |
| Clarity | No uncertainty |
| Efficiency | Short and clear |
| Standard | Internationally understood |
Correct Radio Etiquette
| Rule | Example |
|---|---|
| Always confirm | Acknowledge every instruction with 10-4 |
| Keep it brief | "10-4" is usually sufficient |
| If unclear | "10-4, but please repeat..." |
| Don't overdo it | Not after every sentence |
Origin
The code originates from the APCO-10-Code system, developed in 1940 for the US police. "10-4" became popular through CB radio and trucker culture and is now a global standard – including on film sets.
Today
10-4 is the most commonly used radio confirmation on set. From the director to the PA – everyone knows and uses this code for efficient communication.
More in the lexikon