“In the ordinary sense of the words in the context of service, “to officiate” is to “perform the duties of an office”, and “substantive” means “permanent”. Substantive service therefore means service as a permanent holder of an office, and, in contradistinction, officiating service means service rendered as a non-permanent holder. In fact, all service which is not substantive is officiating, and it seems clear that the words, “whether officiating or substantive” are used in the Regulation to mean “whether substantive or not.” The word “service” by itself without any qualification would ordinarily comprise all service and the words “whether officiating or substantive” are put in brackets after the word “service” only in order to emphasise that all service, of whatever kind, counts. The regulation divides service into two categories, officiating and substantive, and does not contemplate a third, and what it says, is that all service, whether officiating or substantive, counts. It was necessary to clarify that all service, whether officiating or substantive, counts lest
