A 'controlled decking zone' (CDZ) in steel erection is an area where:

解析

A controlled decking zone is a defined area, between 15 and 30 feet above a lower level or at any height where no fall hazard exists below, in which employees placing and securing metal decking at the leading edge need not use conventional fall protection. The price of that relief is strict control: the zone is bounded by control lines, access is limited to those doing the leading-edge work, everyone inside is trained specifically for it, and the decking is laid and secured to the standard's own sequence. Option (b) confuses an access limit with a certification limit. Option (c) reads decking as a stored material rather than as the act of laying it. Option (d) inverts the whole mechanism: inside the zone the conventional requirement is suspended, not tightened.