[Editor’s Note:  Bob Primosch is a Partner with the communications law firm Wilkinson Barker Knauer, LLP, Washington, D.C. (rprimosch at wbklaw dot com)] The FCC has issued a Fourth Notice of Proposed Rulemaking to consider whether it should continue enforcing its “DTV viewability rule” for cable television systems.  In addition, the FCC will consider whether certain…