Paragraph 9

If a click (as opposed to a buzz of appreciable duration) is heard in the monitoring loudspeaker or earphones at any time when any switchgear or controlling apparatus of the radio-frequency heating apparatus is operating, then provided that not more than one further click is heard during the period of two seconds immediately following the first, the readings of the measuring apparatus appearing within that period of two seconds shall be disregarded for the purpose of these Regulations.