A finite number CLAMPED into a declared travel, or null — the value of an OPTIONAL level:
null says nothing is set, so whatever the declaration derives (a floor, a default, a lower
layer) wins again. The numeric half clamps exactly as finiteNumberOf does — a travel
is a travel whether or not it can be vacated — and the whole ControlLimit rides along
so the wire carries unit and step beside the bounds.
A finite number CLAMPED into a declared travel, or
null— the value of an OPTIONAL level:nullsays nothing is set, so whatever the declaration derives (a floor, a default, a lower layer) wins again. The numeric half clamps exactly as finiteNumberOf does — a travel is a travel whether or not it can be vacated — and the whole ControlLimit rides along so the wire carries unit and step beside the bounds.