What that means, plainly
Four promises this page would make - each one Jack has to stand behind before it ships.
[The full range] in every piece. [XS to 3X] on every style we make, not a separate "extended" corner of the store.
[Same price at every size]. Bigger pieces use more fabric. That is our cost to carry, not hers.
Fit-checked, not just graded. [Each size tried on a real body in that size] before a piece goes on sale.
Fit notes per size. Reviews and fit answers are tagged by the size worn, so she reads notes from women built like her.
The range
Placeholder sizing scale - the real range is Jack's to set.
Why this page exists at all
Most stores treat larger sizes as a favor. A modest brand cannot - the whole point is that the woman buying it was pictured from the first sketch. This page says so, in plain words, with nothing on it the store cannot keep.
If a size is ever missing, the waitlist on the product page is the honest answer - and the pattern team hears about every signup.