Comments: PAT *tV- 'to be inside' (also used as a preverb), cf. Abkh. a-tá-la-ra 'enter', Abaz. ta-l-ra id., ta-pa-ra 'jump inside' etc. The root is used also as a noun stem in *tV-ra 'place where' (Abkh. a-t-rá, Abaz. ta-ra ).
PAK *tǝ- (usually with preverbs) 'be, stay, stand'; also used as a preverb "upon the surface of smth.".
In Ub. the root -t(ǝ)- is used as a variant of tʷǝ- 'to be' in some forms (see Vogt 16, 194); historically these are two quite different roots (see PWC *ṕǝ-).