Explanation: When making a routine Digital Selective Calling (DSC) call to another vessel, the primary purpose is to establish contact and then shift to a voice channel for the actual conversation. Therefore, including the **proposed working channel** is essential. The DSC system is designed to automate the calling process, indicating who you want to talk to and on what frequency or channel you intend to speak. This allows the receiving vessel to acknowledge the call and switch to the designated voice channel to begin communication. The time of transmission (A) is typically handled automatically by the DSC system's internal logging or is not a user-inputted part of a routine call. Your vessel’s position (C) is crucial for distress or urgency alerts, but not a standard component of a routine individual DSC call message. The subject matter of the call (D) is reserved for the subsequent voice communication on the working channel, not for the brief DSC signaling message itself.