02 Second Order/Closure Conditions/Terminal
Terminal
Terminal names the boundary where a read stops because continuation crosses a closure scope the current read cannot follow. Where threshold names a located condition that can hold or shift while reading continues, and a crossing hands a read off into the next register, terminal names where reading ends while bearing continues unread beyond the available scale. A terminal is not an end: what is carried continues past it. It names the limit of readability at the current closure scope, not the limit of carrying.
Trace
Read
Terminal becomes recognisable where a read can no longer be followed across a boundary, not because carrying has ceased, but because continuation has crossed into a closure scope unavailable to the current read.
Structural Role
Terminal is a second-order closure condition. It is the class of read-stops: a crossing whose far side the current closure scope cannot open. Ground is the terminal below, a black hole the terminal across. Collapse is a terminal read as an end where the carrying past it falls outside scale.