Comments:Poppe 104, Menges 1982, 105, Дыбо 13. A Western isogloss. There exists also a not quite reliable variant *t`abi id. (Mong. tab 'clinch, rivet'; TM *tabi- 'to forge' (ТМС 2, 149, with yet another variant *tabi-ti- > *tapti- / *tipti- id., see ibid. and ТМС 2, 186).