-options                PORTAL          # ?
   +options                PORTAL          # create sockets with open(2)

> That's really not what portal fs does.  The portal daemon can create
> any arbitrary file descriptor (perhaps even a pipe from another
> program) and pass it back.

True, but think about the description's context.  It's a comment in a
CONFIG file (where vnd is described a "paging to files", not "provides
a block special interface to another type of vnode".)

You can use whatever you want of course.

~Ken