KALAMAZOO (WKZO) -- The Kalamazoo City Commission will vote Tuesday night on a proposal to enact a six-month moratorium on all billboard activity.  The commission had been asked to approve a plan for four digital billboards, but officials felt they needed more time to study the technology.  If the moratorium passes, city staff will have half-a-year to look into changing ordinances to take into account the size of the ads, the brightness of the LED billboards, how often the images can change and where they could be located in the city.