Explanation: VHF-DSC (Digital Selective Calling) transceivers operate on precise, pre-defined channels, primarily using FM for voice communication and GMSK for digital calls. **"R.I.T." (Receiver Incremental Tuning)** is a control typically found on HF transceivers, particularly those used for single-sideband (SSB) or Morse code (CW) operation. Its purpose is to allow a slight adjustment of the receiver frequency independent of the transmit frequency, compensating for minor frequency drift or slight differences between stations. VHF-DSC radios operate with precise, crystal-controlled or synthesized channels and don't require this fine, independent tuning capability, making R.I.T. unnecessary. In contrast: * A **"Distress" button** is a core function of any DSC radio, allowing for the automated transmission of a digital distress alert. * A **"Cancel" button** is essential for aborting an accidentally initiated distress call, preventing false alarms. * A **"Squelch"** control is a standard feature on virtually all FM transceivers, including VHF marine radios, used to mute receiver audio noise when no signal is present.