They should specify HRUI, to differentiate between riding a horse under the influence, and riding a camel under the influence (CRUI -- like some innocent refugee members of the religion of peace might sometimes try to do).
(Now, if the horse is under the influence, they should call that "HUI".)
12 posted on 02/25/2018 2:58:08 PM PST by Songcraft
("Pray without ceasing." 1 Thessalonians 5:17)