Most contractors see F-numbers in the majority of specifications written today and most have read articles and publications on the subject. F-numbers have been around long enough for most contractors to be comfortable with them both in bidding as well as in the construction process. In many cases, however, contractors have become too comfortable or complacent with F-numbers. If F-number specifications are written improperly or are incomplete, they can create controversy. For example, specifications for random-traffic floors must include both FF (flatness) and FL (levelness) tolerances. However, the levelness tolerance should not apply to slabs placed on unsupported form surfaces or to cambered or inclined slab surfaces. In other words, if a contractor is asked to slope areas of a slab to drains or slope a section of slab to meet an existing slab, then the FL portion of the specification is automatically invalid for those areas. When F-number specifications are not measured and compliance is not confirmed, the system is abused along with the unsuccessful contractors who bid the job with the intent of meeting the specifications. If measurements are not taken, contractors are no better off than they were with the gap-under-a-straightedge specification.