Explanation: Channel 70 is specifically and exclusively allocated for Digital Selective Calling (DSC) on VHF marine radios. DSC is a non-voice, digital signaling system designed for transmitting distress alerts, urgent calls, safety messages, and routine calls to specific stations or groups of stations. Its dedicated use ensures rapid and reliable digital communication without interference from voice traffic. In contrast: * **Channel 16** is the international voice calling and distress frequency, continuously monitored for urgent voice communications. * **Channel 22A** is primarily used for public correspondence and U.S. Coast Guard safety broadcasts, often after initial voice contact on Channel 16. * **Channel 6** is designated for intership (ship-to-ship) safety communications via voice. These other channels serve various voice communication purposes, unlike Channel 70, which is reserved *only* for digital selective calling.