This excerpt taken from the ELN 6-K filed Mar 31, 2006.
Impairment of Goodwill and Other Intangible Assets
Goodwill, intangible assets with an indefinite useful life and intangible assets not yet available for use are not subject to amortisation and are tested for impairment at least annually. Additionally, these assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. The recoverable amount is the higher of an assets fair value less costs to sell and value in use. Value in use is calculated by discounting the expected future cash flows obtainable as a result of the assets continued use. For the purposes of impairment testing, assets are grouped at the lowest
36 Elan Corporation, plc 2005 Annual Report