BC481 Before the issuance of IFRS 15, there were significant differences in accounting for economically similar revenue transactions, both within and across industries for entities applying US GAAP. There was also significant diversity in practice in accounting for revenue transactions for entities applying IFRS. Those differences made it difficult for users of financial statements to understand and compare revenue numbers. As explained in paragraphs BC460-BC480, some of this diversity arose because there were limited revenue recognition requirements in IFRS in general and on particular topics. Furthermore, the requirements that were provided were difficult to apply to complex transactions, in part because there was no rationale for those requirements (ie there was no Basis for Conclusions). Those differences also arose because previous revenue recognition requirements in US GAAP were voluminous and often industry-specific or transaction-specific, which also created difficulty for users of financial statements in interpreting the information about revenue. The boards noted that the diversity in practice and challenges to users were often amplified for entities applying IFRS because some preparers selectively referenced US GAAP.