the santa cruz operation (sco), owners of xenix, eventually acquired the unixware trademark and the distribution rights to the system v release 4.2 codebase from novell, while other vendors (sun, ibm, hp) continued to use and extend system v release 4. novell transferred ownership of the unix trademark to the open group. any operating system that meets the single unix specification (sus), effectively a successor to the system v interface definition, may be granted unix rights. the sus is met by apple's macos, a bsd derivative, as well as several other operating systems not derived from either bsd or system v.