SBRimpairment reversal

found this question in the BPP study text. does anyone know why there no impairment reversal on the patent? what do they mean by "more advanced model"? A cash generating unit comprising a factory, plant and equipment etc and associated purchased goodwill becomes impaired because the product it makes is overtaken by a technologically more advanced model produced by a competitor. The recoverable amount of the cash generating unit falls to $60m, resulting in an impairment loss of $80m, allocated as follows: Carrying amounts before impairment ( $m ) Goodwill 40 Patent (with no market value) 20 Tangible long-term assets 80 Total 140 Carrying amounts after impairment ( $m ) Goodwill 0 Patent (with no market value) 0 Tangible long-term assets 60 Total 60 After three years, the entity makes a technological breakthrough of its own, and the recoverable amount of the cash generating unit increases to $90m. The carrying amount of the tangible long-term assets had the impairment not occurred would have been $70m. Required Calculate the reversal of the impairment loss. Answer The reversal of the impairment loss is recognised to the extent that it increases the carrying amount of the tangible non-current assets to what it would have been had the impairment not taken place, ie a reversal of the impairment loss of $10m is recognised and the tangible non-current assets written back to $70m. Reversal of the impairment is not recognised in relation to the goodwill and patent because the effect of the external event that caused the original impairment has not reversed – the original product is still overtaken by a more advanced model