Q codes are a set of formalized abbreviations for use in various kinds of radio services. They are so named, because they all start with the letter Q. All are also exactly three letters long.
The base form of the Q code is either a request or a piece of information, e.g. QRO = Please increase your transmitter power, or QTP = I will arrive at seaport. The codes may be turned into questions by appending a question mark, ?. Answers to such questions are in the format of the base code, appended by C (for the affirmative), or NO (for the negative). This is rather a lot like the UI and COI cmavo of Lojban.
| Q code | attitudinal | |||
| Base form | QSL | .ui | ||
| Question form | QSL? | .uipei | ||
| Affirmative | QSLC | .ui | ||
| Negative | QSLNO | .uinai | ||
As we can see in the above table, the corresponding attitudinal expressions for base forms and affirmative forms are the same, while the Q codes are different.