In
https://www.w3.org/TR/2019/CR-css-writing-modes-3-20190903/
the SVG image
https://www.w3.org/TR/2019/CR-css-writing-modes-3-20190903/images/orthogonal.svg
in Example 11 of section 7.3 Orthogonal Flows
uses "extent" and "measure" which are not defined anywhere; these are remainings of older versions.

Proposed corrections:
"measure" should be replaced by "inline size".
"extent" should be replaced by "block size".