The chains the extension cannot be taken off, being no longer than it
is: the reader reported them open for less time than it holds a valve
on beyond the perforation, so the constant over-corrects them and
would leave them ending before they begin.
They are where the constant shows its limit rather than where the
copy is wrong, the extension varying by about half a millimetre with
the port. What to do with them is an editorial question — a condition
on the feature, a reading of the chain, a smaller extension — and
shortenChains throws rather than answer it.
The chains the extension cannot be taken off, being no longer than it is: the reader reported them open for less time than it holds a valve on beyond the perforation, so the constant over-corrects them and would leave them ending before they begin.
They are where the constant shows its limit rather than where the copy is wrong, the extension varying by about half a millimetre with the port. What to do with them is an editorial question — a condition on the feature, a reading of the chain, a smaller extension — and
shortenChainsthrows rather than answer it.