For intangible assets with finite lives, the amortization method should reflect the pattern of decline in the economic usefulness of the asset. If no such pattern is apparent, the straight-line method of amortization should be used. The amount to be amortized should be the value assigned to the intangible asset less any residual value. In most cases, the residual value is presumed to be zero. However, that presumption can be overcome if the acquiring enterprise has a commitment from a third party to purchase the intangible at the end of its useful life or an observable market exists for the intangible asset.