Each of the three previous chapters described analytical methods appropriate for studying some feature of natural gas markets. The pur­ pose of such studies would be to obtain a suffi­ cient understanding of the forces at work in natural gas markets to predict their evolution, to assess their performance, and to design remedial policies (if needed). In this chapter we describe two issues that are both broad and likely to re­ main unresolved for some time, so as to illus­ trate how the products of a systematic research effort could be used. The issues addressed relate to: (1) the regulatory and carrier status of pipe­ lines, and (2) rules regarding the allocation of costs in downstream rate structure.