Residents of Zenica have been called to gather in the streets over problems with the city's heating system. Their protest is timed to coincide with another session in which the city council will debate heating. Organizers are asking people to bring blankets so they can remain outside for an extended period. Demonstrators have also been urged to bring whistles and a copy of a heating bill they have paid. The action makes both heating costs and service reliability central to the dispute with officials. It is the latest public pressure on the council to address the issue.