Notes: One of the rare verbal roots with the root structure *HRVCV: such a reconstruction is directly suggested by the Lak. reflex t:irix:i-. Other languages have modified the structure of the root (we would expect *dirix:- in PD and *raʎɨ- in PL), having reinterpreted its Anlaut as a morphological prefix. The root demonstrates the verbal Ablaut *a/i.
See Trubetzkoy 1922, 240 (and comments on p. 443).