Some of the RelEx2Logic rules requires this though.  For example the det-rule is using relation _det that can only be reached by following sf-links (you will not find _det anywhere by following the normal "links").  sf-links are available on the Feature Structure I am testing on, so it seems be generated.  On the other hand I was using the plain-text-server.sh script to start the Relex server, maybe it's different from using the opencog-server.sh script.