For the most part, multiple slashes are equivalent to a single slash. There's one exception: paths beginning with exactly two slashes (//foo/…, as opposed to /foo/… or ///foo/…) have a different meaning on some Unix variants. The meaning is often to access a remote resource with a path like //hostname/dir1/dir2/dir3/file. (Windows does this too, with \\hostname\dir1\dir2\dir3\file.)

QNX is one of those variants. On QNX4 with the FLEET distributed processing protocol, // followed by a number refers to that node. So ``//1/usr/pvcson any node refers to the file/usr/pvcs` on node 1.

(Source: the QNX6 manual, I can't find official QNX4 documentation online.)

For the most part, multiple slashes are equivalent to a single slash. There's one exception: paths beginning with exactly two slashes (//foo/…, as opposed to /foo/… or ///foo/…) have a different meaning on some Unix variants. The meaning is often to access a remote resource with a path like //hostname/dir1/dir2/dir3/file. (Windows does this too, with \\hostname\dir1\dir2\dir3\file.)

QNX is one of those variants. On QNX4 with the FLEET distributed processing protocol, // followed by a number refers to that node. So //1/usr/pvcs on any node refers to the file /usr/pvcs on node 1.

(Source: the QNX6 manual, I can't find official QNX4 documentation online.)