Time to brush up on the army talk:
10-4 — Message received; I understand; ok; all right Affirmative / Affirm — Yes
Break — Signals a pause during a long transmission to open the channel for other transmissions, especially for allowing any potential emergency traffic to get through.
Break-Break — Signals to all listeners on the frequency, the message to follow is priority. Almost always reserved for emergency traffic or in NATO forces, an urgent 9 line or Frag-O. In Aviation it simply signifies the end of a transmission to one call-sign and the commencement of transmission to another. e.g. "G-WXYZ Standby. Break-Break. G-ABCD Cleared to Land Runway 17" etc.
Callsign-Actual/Callsign-Niner — Sometimes an individual (generally a superior) may have a person monitor the network for them. Saying "actual" after their callsign asserts you wish to speak to the specific person the callsign is attached to. ex: calling the callsign "Headquarters" would often get junior clerk or similar. Calling (or identifying yourself as) "Headquarters-Actual" would indicate that the commander of the headquarters detachment, and thus the entire unit to which it is attached, is requested to be spoken to, or is actually speaking. (In Canadian use, this is Callsign-Niner, with "9" designating a unit commander. An individual monitoring the net but is not the actual commander may used the call-sign "Niner-Zulu". As well, the codeword "Sunray" is also used to designate a unit commander.)
Come in — You may begin speaking now
Copy (U.S.) — I heard what you just said; ok; all right. Falcon — prefix followed by a (usually three-digit) code number for an Army creole phrase.
Go ahead or Send your traffic — Send your transmission.
Mayday — Maritime/aviation distress call. Repeated three times and at beginning of every following transmission relating to the current distress situation. Has priority over urgency and safety calls.
Negative — No
Out — I have finished talking to you and do not expect a reply.
Over — I have finished talking and I am listening for your reply. Short for "Over to you."
Pan-pan — Maritime/aviation urgency call. Repeated three times. Has priority over safety calls.
Reading you Five / Loud and clear / Your signal is clear; 5×5.
Ready to Copy — Write down (e.g. "Prepare to copy" - I am going to give you detailed instructions, have something ready to write them down with; or 'I am ready to write down' when used in a reply transmission).
Roger — "I have received all of the last transmission" in both military and civilian aviation radio communications. This usage comes from the initial R of received: R was called Roger in the radio alphabets or spelling alphabets in use by the military at the time of the invention of the radio, such as the Joint Army/Navy Phonetic Alphabet and RAF phonetic alphabet. Contrary to popular belief, Roger does not mean or imply both "received" and "I will comply." That distinction goes to the contraction wilco (from, "will comply"), which is used exclusively if the speaker intends to say "received and will comply". The phrase "Roger Wilco" is procedurally incorrect, as it is redundant with respect to the intent to say "received"
Roger So Far — Confirm you have received and understood the contents of my transmission so far. This is used during Long Message Procedure (Messages lasting over 20 seconds prefixed by the Pro-Word 'Long Message' and the initiating C/S must give a gap of five seconds after the receiving station has replied with 'Roger'. This five seconds is to allow other Stations onto the net if they have important messages.
Say again repeat; Please repeat your last message (Repeat is only used in Australian/Canadian/UK/US military radio terminology to request additional artillery fire)
Standby or Wait out — Pause for the next transmission. This does not usually entail staying off the air until the operator returns as they have used the word 'Out', which indicates the transmission has ended. The net is now free for other traffic to flow but users should be aware that the previous C/S may re-initiate a Call as per their 'Wait out'. As with 'Wait', this can be appended with a number to indicate estimated number of minutes. For example: "We are on the phone with them trying to sort this out, standby five." Wait — I do not have the answer or information to hand, I will attempt to source the answer or information requested shortly but until then I have finished talking and do not expect a reply. Can be suffixed with a number to indicate estimated number of minutes until a reply can be expected. ex: WAIT TWO indicates "you should expect my reply in approximately two minutes."
Wilco — Will comply (after receiving new directions, implies Roger).