Acknowledging Message, e.g. Copy that or Roger

1. What is difference between copy that and Roger that?
2. Is it OK to say Roger that?
3. What do you say in response to Roger that?
4. Can we use Roger that in email?

What is difference between copy that and Roger that?

“Copy that” is used only to acknowledge information, and there's usually no need to act on that information. Whereas the phrase “roger that” is used to acknowledge some information or instruction, and the receiver will take action upon it.

Is it OK to say Roger that?

While in the current spelling alphabet (NATO), R is now Romeo, Roger has remained the response meaning "received" in radio voice procedure. In the US military, it is common to reply to another's assertion with "Roger that", meaning: "I agree".

What do you say in response to Roger that?

Taking it a step further, some may know "Roger" as part of the full reply "Roger Wilco." Translated into typical English, that phrase actually means "Received, will comply."

Can we use Roger that in email?

“Roger that," "copy," or "10-4.” The police and military have used these practices since the early '70s to acknowledge received messages.