Considering that $cc comes from %Config, it could technically contain anything. For instance, it may contain "/foo/bar/:[baz]". Now, while the latter is valid in most Unix file systems, it's highly unlikely to find a C compiler in such a path. Unlike VMS. A full path in VMS consists of a device name, a directory, a file name (including extension), and a version number. The device name and the directory are separated by a colon, while the directory itself is enclosed in square brackets. Which explains not only that $cc may match this, but also why this specific match was choosen.