EPUB Accessibility

EPUB  is an international standard based on HTML. They have an
accessibility standard https://www.w3.org/TR/epub-a11y-11/. This is tied to
WCAG 2.1. This is good. If the reflow criterion  1.4.10 is needed anywhere,
it is needed in published books, articles, monographs etc.
There is a "fixed format" for ebooks. This is inaccessible categorically.
I  hope that  this  is  called out by the EPUB organization in its
literature  on accessibility.
When we address the overhead cost of 2-dimensional scrolling for articles,
monographs and books we are talking about thousands, tens  of thousands and
hundreds of thousands of scrolls.
There are no textbooks in mathematics beyond  calculus that reflow, and I
only know  of one calculus that reflows.
Special attention should  be given to  STEM textbooks. Lack of accessible
STEM textbooks is the reason for low participation in STEM subjects for
people with print disabilities. It is very difficult to succeed in a course
when you don't have a textbook.
best, Wayne