Encyclopædia Britannica, Ninth Edition/Udal

UDAL (Danish odel) is a kind of right still existing in Orkney and Shetland, and supposed to be a relic of the old allodial mode of landholding existing antecedently to the growth of feudalism in Scotland. The udal tenant holds without charter by uninterrupted possession on payment to the crown, the kirk, or a grantee from the crown of a tribute called scat (Danish skat), or without such payment, the latter right being more strictly the udal right. Udal lands descend to all the children equally. They are convertible into feus at the option of the udallers.