         const size_t curMinSP = OTV0P2BASE::MemoryChecks::getMinSP();
         const uint8_t txMinSP = (255U >= curMinSP) ? (uint8_t) curMinSP : 255U;
         ss1.put(V0p2_SENSOR_TAG_F("SP"), txMinSP, true);
-        // OPTIONAL items
+
+        // Always TX in this case, as channel is secure.
         constexpr uint8_t privacyLevel = OTV0P2BASE::stTXalwaysAll;
 
         // Redirect JSON output appropriately.

 * INTERRUPT SERVICE ROUTINES
 *****************************************************************************/

// Controller's view of Least Significant Digits of the current (local) time, in this case whole seconds.
// Previous state of port B pins to help detect changes.
//
// NOTE: PrimaryRadio may switch PCINT0 on and off during operation! This pin bank should not be relied

        // frame-length byte for encrypted frame.
        uint8_t *const realTXFrameStart = sW.buf + 1;

        // Forcing encryption so suppress the "@" and "+" ID fields,
        // assuming that the encrypted commands will carry these in the 'envelope'.
        ss1.setID(V0p2_SENSOR_TAG_F(""));
        ss1.enableCount(false);

        // Managed JSON stats.
        // Show internal temperature of boiler hub.
        ss1.put(TemperatureC16);
        // Show boiler state for boiler hubs.
