I think a minimal change that would restore correctness would be
something like
================
The vectors of upper and lower bounds of an interval can have zero
elements, in which case the zero-dimensional interval itself has no
elements, but zero-dimensional arrays with this domain have getters and
setters that take zero indices as arguments, and which return or set a
single element, much like a Scheme box.
================
to
================
The vectors of upper and lower bounds of an interval can have zero
elements; zero-dimensional arrays with this domain have getters and
setters that take zero indices as arguments and return or set a single
element, much like a Scheme box.
================
This just gets rid of the incorrect phrase without trying to make a
longer explanation.

Brad