The listbox note for horizontal listbox keyboard UX is confusing.

[rhdunn]

The note in https://www.w3.org/TR/2019/NOTE-wai-aria-practices-1.1-20190814/#listbox_kbd_interaction states:

5. If the options in a listbox are arranged horizontally:
   1. Down Arrow performs as Right Arrow is described above, and vice versa.
   2. Up Arrow performs as Left Arrow is described above, and vice versa.

This is confusing because:

1. Right/Left Arrow are not described above, only Down/Up Arrow.
2. I would expect a horizontal orientation to imply the use of Right/Left Arrow keys, so would have expected the use of Down/Right and Up/Left in the text to be the other way around.
3. It is not clear whether both or only the orientation specific set of arrow keys should be supported.

Additionally, to make it clearer, these should be specified in the main keyboard section instead of as a note.

[ZoeBijl]

This text is unchanged in the editor’s draft: https://w3c.github.io/aria-practices/#Listbox