LEGAL

Accessibility Statement

Every reader should be able to reach the text.

Our aim

The editorial desk wishes the reference to be readable by as many people as possible, including readers who use a screen reader, readers who navigate by keyboard alone, readers who enlarge the text, and readers who prefer reduced motion or increased contrast. Accessibility is treated here as part of the ordinary craft of putting words on a page, not as an afterthought bolted on at the end.

What has been done

The pages use a clear heading order, so that a reader who moves from heading to heading meets the structure of the argument rather than a jumble of fragments. Each page carries a single main heading, and the sections beneath it are marked with lower-level headings in sequence. Links are written so that their text makes sense out of context, and no link is presented as a bare direction such as “here”.

The colour scheme uses a dark ink on a light ground, and the accent colours were chosen for contrast rather than for decoration. The body text is set at a comfortable size and with generous line spacing, so that a reader who does not enlarge anything still finds the pages easy on the eye, and a reader who enlarges the text does not lose the layout.

The diagrams are drawn as vector shapes embedded in the pages, and each carries a short text alternative that names what it shows. A reader who cannot see a diagram can therefore still follow the surrounding argument, because the text does not depend on the illustration for its sense.

Navigation

The section rail at the top of each page is built from ordinary page elements and can be reached and opened with a keyboard alone. On a narrow display the rail becomes a plain vertical list with every page visible at once, so that no pointer gesture is required to reveal the contents. The footer repeats the whole arrangement as a table of links, which gives a reader a second, independent route to every page.

Motion and animation

The reference contains no animation, no automatic movement and no element that changes on its own. A page therefore stays still while a reader works through it, and the reading position is never lost to a moving element. This choice is deliberate: a quiet page is easier to study, and it is kinder to readers who find movement distracting.

Known limits

The desk is aware that no page can be made perfect for every reader and every display. Some very old browsers may not render the vector diagrams, though the text will remain readable. Some screen readers handle mathematical notation differently from one another, and the desk has tried to keep the notation simple and consistent for that reason.

Tell us

If you meet a barrier on these pages, please write to the desk through the contact page and describe what happened, including the page and the action you took. Reports of this kind are treated as corrections, and they are among the most useful messages the desk receives. Related pages are the Terms of Use and the Privacy Policy.