(1) Where a person incurs capital expenditure on the purchase of patent rights and, before the end of the writing-down period, any of the following events occurs -
(a) the rights come to an end without being subsequently revived;
(b) the person sells all those rights or so much of those rights as the person still owns;
(c) the person sells part of those rights and the net proceeds of the sale (in so far as they consist of capital sums) are not less than the amount of the capital expenditure remaining unallowed;
no writing-down allowance shall be made to that person for the chargeable period related to the event or for any subsequent chargeable period.
(2) Where a person incurs capital expenditure on the purchase of patent rights and, before the end of the writing-down period, either of the following events occurs -
(a) the rights come to an end without being subsequently revived;
(b) the person sells all those rights or so much of those rights as the person still owns, and the net proc
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