Trade secret law, copyright law, and patent law each offer a different treatment for claims to interface ownership. Software developers have long sought to protect interface information as trade secrets because it cannot be discerned readily by the user, but the fact that software availability makes a system desirable gave companies an incentive to make interface data public. The Congressional Commission on New Technological Uses of Copyrighted Works (CONTU) recommended in the late 1970s that software be protected under copyright law rather than trade-secret law. The questions of whether copying an interface to make compatible software would be an infringement and of when trade secrets and copyrights would coexist remained unclear. Software firms have claimed both trade-secret and copyright claims in the 1980s. Many software licenses prohibit reverse engineering, which would enable a firm to independently develop compatible products. Intellectual-property law still struggles to distinguish between'ideas'(which may be copied) and their'expression'(which copyright law protects). NEC Corp successfully defended its reverse-engineering of Intel microprocessors on the basis of compatibility and the fact that the similarities between the two firms' microcodes were essentially functional. Many software firms may resort to patents if they cannot protect popular software interfaces under trade secret or copyright law. Atari Inc's pending lawsuit against Nintendo charges that Nintendo is using its patented interface to prevent Atari from developing compatible video-game software. Atari argues that the Nintendo interface is not'novel,'as required by patent law.