Portions of the source or object code of a computer program are rarely

filtered out as unprotectable elements. However, some distinct parts of

source and object code have been found unprotectable. For example,

perform calculations in a program, are unprotectable. Further, although

common errors found in two programs can provide strong evidence of

copying, they are not afforded any copyright protection over and above the

that in Adapter. After the suit began, the defendant rewrote those

portions of Oscar that contained Adapter code in order to produce a new

version of Oscar that was functionally competitive with Adapter, without

plaintiff alleged that even the second version of Oscar, despite having no

literally copied code, also infringed its copyrights. In addressing that

question, the Second Circuit promulgated the AFC test.