A CwrRFZeroIndex, read-create, identifying which RF resource this histogram specification applies to, where 0 tells the agent to pick automatically. On multi-radio wireless cards this ties the histogram to one specific radio chain rather than the whole unit, and reading it back after setting 0 reveals which radio the agent actually chose. For example, on a unit with both a main and diversity radio, leaving cwrRfResourceId at 0 for a transmit-power histogram lets the agent decide which radio chain is the relevant one to capture.