Position Principle

The Position Principle is the second governing principle of the Zero Information Casualty standard:

Equivalent access does not require identical interaction. It requires that every reader can reach the same informational and orientational position through a mechanism appropriate to their channel.

The sighted reader sees the hierarchy; the screen reader user hears headings and landmarks; the keyboard user is handed a skip link; the agent parses the page. They don't behave alike and couldn't. The equivalence is not of experience but of position: each, by a different road, arrives knowing where the content is, how it is organised and how to go on.

Two principles, two jobs

The Single-Sense Rule governs how information is encoded. The Position Principle governs whether it arrives. A page can pass the first and fail the second, with every fact in the semantic layer and one class of reader still labouring towards what another gets at a glance. Conformance needs both.

Structural information

The principle explains two requirements that look like human courtesies. The main content starts here is a fact: the eye gets it by glance, the agent from the main element, the screen reader user from landmarks, and the sighted keyboard user from nothing at all, unless a skip link supplies it. The skip link is the keyboard rendering of that fact. Likewise, the focus ring is the only rendering of where am I? that a sighted keyboard user has.

Bounded

The principle binds through the requirements derived from it, not directly. An auditor may not invent a new failure from it, because labour has no threshold, and taken literally it would convict every page ever built. "The principle governs the standard. The requirements govern the site."

Behind the scenes

A real idea, from Zero Information Casualty v1.7, the design standard by Charli-Jo Tyrer and Claude, §1.15 and §1.16. This entry summarises it; the standard is the authority.