Explanation: The GMDSS radio log is a vital document that records all distress, urgency, safety, and routine communications, as well as equipment tests and significant events related to the ship's radio station. International regulations, notably the Safety of Life at Sea (SOLAS) Convention, and national regulations like FCC Part 80, mandate that this log be maintained and kept readily accessible. Storing the log directly at the GMDSS operating position ensures that the operator on watch has immediate access to past entries, operational procedures, and contact information. This is crucial for efficient operation, especially during emergencies, when quick reference to previous communications or test results can be critical for safety. Keeping it elsewhere, such as the Captain's office or a sea cabin, would delay access, compromise operational efficiency, and violate regulatory requirements for immediate availability at the control point. "Anywhere on board" fails to meet the specific accessibility requirement.