Yes "dark" is the right term. It means no telco is lighting it with their SONET or whatever equipment and then selling me a managed service. We have 20-year rights to several strands of actual glass end-to-end which we can light with whatever we want. We could send morse code by flashlight (torch for the bloody UK poster:-) but instead we chose to start with 10 gigabit Ethernet. I think the term you are looking for describing previsouly laid and unproductive fiber is "distressed assets." ;-)