It can depend. Usually Zoniing regulations would cover the display of the signs, but building regulations would address the way they are constructed and hung or placed on the building.
Up-regulation is where a cell creates more receptor due to little ligand activity. Down-regulation is the opposite. They are caused by intracelluar processes.
Line regulation defines as the output voltage of the zener to remain constant under input line variation. Load regulations defined as the load increases or decreases the zener will control this...