A code used by CB owners possibly since the dawn of amateur radio, the code 10-4 simply means "Message received". Since the 70s the code system have been popular in law-enforcement circles then evolved to what it is today. Nowadays when people use these codes, they are mostly refering to the police radio code system, which is more detailed then its original version, so I'am only listing the police code system here rather than the out dated CB code version.
Please note that these code vary from one country to another or even used differntly in differnt state/province in the same country
10-0 Use Caution 10-1 You are being received Poorly 10-2 You are being received Clearly 10-3 Stop Transmitting 10-4 O.K. 10-5 Relay Message 10-6 Busy with Call 10-7 Out of service, (completely) 10-7b Out of service (personal) 10-7c Out of service (court) 10-7od Out of service (off duty) 10-8 In service 10-8ot In service (over time) 10-9 Repeat last message 10-10 Out of service, Radio on 10-11 Give F.C.C. Call Sign/Dispatching too fast 10-12 Visitors or officials present 10-13 Advise weather and road conditions 10-14 Convoy or escort detail 10-15 Prisoner in custody 10-15m Prisoner in custody (mental case) 10-16 Pick up prisoner 10-17 Pick up papers 10-18 Complete present assignment ASAP/Get there ASAP 10-19 Return to office 10-20 Your location 10-21 Call by telephone 10-21A Phone home, my ETA is _____ 10-21B Call your home 10-22 Cancel last message/Take no further action 10-23 Stand by until channel clears 10-24 Emergency at station/all units return 10-25 Do you have contact with ___________ 10-26 Driver's license check by number or name 10-27 Check for wants or warrants 10-28 Check registration on vehicle 10-29 Check for stolen for 10-29A Check wants, subject (PIN) 10-29R Check wants and record, subject (PIN, CJIC) 10-29C Check complete, subject (NCIC) 10-30 Does not conform to rules or regulations 10-31 Is lie detector available? 10-32 Man with gun. 10-33 Emergency traffic/don't transmit unless necessary 10-33 Alarm (type: Audible, silent) 10-34 Clear for local dispatch or open door 10-35 Confidential information or open window 10-36 Correct time 10-37 Give me name of Operator on duty 10-38 Your destination 10-39 Your message is delivered/Requested unit in route 10-40 Advise if officer _______ available for phone call 10-41 Call the station on alternate frequency 10-42 Officer ..... now at his home 10-43 Have _________ call his/her residence 10-44 Station _________ is calling your residence 10-45 Give name of Officer in Charge or Injured person 10-46 Advise if ________ available at phone 10-47 Officer ______ is available at _________ 10-48 Not available for assignment/out for coffee or whatever 10-49 Pick up passenger at ___________ 10-50 No traffic for you/resume patrol 10-51 Message for delivery by telephone 10-52 Message for delivery in writing 10-53 Do you have traffic for this station? 10-54 Unit and officer have left the Parish 10-54d Possible dead body 10-55 Unit and officer have returned to Parish 10-55d Send coroner 10-56 Teletype busy 10-57 Teletype broken or Firearms discharged 10-58 Teletype in service 10-59 Tape for repeat message 10-60 What is next for message # _____ 10-61 Stand by for teletype message 10-62 Unable to copy radio, use teletype or meet in person 10-63 Net in use, stand by, will advise when clear 10-64 Net clear, go ahead with traffic 10-65 Clear for assignment 10-66 Clear for cancellation 10-67 All stations retransmit following 10-68 Repeat dispatch 10-69 Have you dispatched _______? 10-70 Net message for all stations 10-71 Proceed with traffic 10-72 Stand by for Civil Defense Test 10-73 Stand by for Civil Defense Traffic 10-74 Civil Defense Clear 10-75 Severe weather statement 10-76 Give daily traffic 10-77 Give mileage your unit 10-78 Send ambulance 10-79 Send wrecker 10-80 Tower lights out/Explosion/Lightening 10-80a Assist radio dispatcher 10-81 Officer ______ will be at your station 10-82 Reserve room for officer 10-83 Have _______ call station by phone 10-84 Advise ____ officer will return this date 10-85 Officer _____ on special detail or Meet with agent 10-86 Advise phone number your location 10-87 Give call letters of your station 10-88 Advise phone number of officer 10-89 Request radio servicemen be sent 10-90 Request teletype servicemen 10-91 Prepare for inspection of ______ by ________ 10-91B Noisy animal (Barking) 10-91D Dead animal 10-91H Stray Horse 10-92 Your quality is poor 10-93 Your quality is good 10-94 Call station by teletype 10-95 Advise telephone call this station 10-96 Give test count 10-97 Arrived at scene 10-98 Last detail completed 10-99 Unable to receive your message 10-100 Out using restroom 10-102 Cruelty to animals 10-103 Disturbance 10-103f Disturbance by fight 10-103m Disturbance by mental person 10-106 Obscenity 10-107 Suspicious person 10-108 Officer down or Officer needs assistance 10-112 Impersonating an officer 11-6 Illegal discharge of firearms 11-7 Prowler 11-8 Person down 11-10 Take a report 11-12 Dead animal 11-13 Injured animal 11-14 Animal bite 11-15 Ball game in street 11-17 Wires down 11-24 Abandoned Vehicle 11-25 Vehicle - Traffic hazard 11-25X Female motorist need assistance 11-26 Abandoned bicycle 11-27 Subject has felony record, but is not wanted 11-28 Rush vehicle registration information 11-29 Subject has no record 11-30 Incomplete telephone call 11-31 Person calling for help 11-40 Advise station if ambulance is needed 11-41 Request Ambulance 11-42 Ambulance not required 11-43 Doctor required 11-44 Coroner required 11-45 Attempted suicide 11-46 Death report 11-47 Injured Person 11-48 Provide Transportation 11-54 Suspicious vehicle 11-65 Traffic Signal light out 11-66 Traffic Signal Out-of-order 11-70 Fire Alarm 11-71 Fire Report 11-79 Traffic Accident - Ambulance dispatched 11-80 Traffic Accident - Serious Injury 11-81 Traffic Accident - Minor Injury 11-82 Traffic Accident - No Injury 11-83 Traffic Accident - No Details 11-84 Direct Traffic 11-85 Dispatched Tow Truck 11-86 Special Detail 11-87 Assist Other Unit 11-95 Out of vehicle, car stop (location/license) 11-96 Out of vehicle, car stop, send backup(location/license) 11-98 Meet Officer 11-99 Officer needs Help/Emergency