There are no rules or authoritative guidelines that define tangible book value. Tangible book value per share is used generally as a conservative measure of net worth, approximating liquidation value. The staff believes generally that tangible assets should exclude any intangible asset (such as deferred costs or goodwill) that cannot be sold separately from all other assets of the business, and should exclude any other intangible asset for which recovery of book value is subject to significant uncertainty or illiquidity.