(1) For the purposes of this Chapter, a building or structure shall not be deemed to cease altogether to be used by reason that it is temporarily out of use and where, immediately before any period of temporary disuse, a building or structure is an industrial building or structure, it shall be deemed to continue to be an industrial building or structure during the period of temporary disuse.
(a) Notwithstanding any other provision of this Part as to the manner of making allowances and charges but subject to paragraph (b), where by virtue of subsection (1) a building or structure is deemed to continue to be an industrial building or structure while temporarily out of use, then, if -
(i) on the last occasion on which the building or structure was in use as an industrial building or structure, it was in use for the purposes of a trade which has since been permanently discontinued, or
(ii) on the last occasion on which the building or structure was in use as an industrial building or s
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