Issue

Fixes #40

Details

Implements the position and group algorithm for appropriate roles allowing calculation of roles that have implicit aria-posinset and aria-setsize support.

REF: https://www.w3.org/TR/core-aam-1.2/#mapping_additional_position

Updates aria-level to support additional roles that have implicit values calculated by document structure.

REF: https://www.w3.org/TR/wai-aria-1.2/#aria-level

Breaking change: aria-posinset and aria-setsize are now announced as position and set size respectively, instead of item set position and item set size.

CheckList

• Has been tested (where required).