Das: = rung, fit, becoming, convenient, practicable. CM: bla'am rung ba dang thub pa, easy or fit and possible/practicable. E.g, btung du btub, fit to drink/potable. bzhon du btub, fit to mount/fit as a mount [said of a horse?] or fit to ride (?) [said of a vehicle]. las don che chung gang yang byed btub pa, able to do any undertaking, great or small. ji tsam smras kyang nyan mi btub pa, However much/Whatever he says, it is not fit to be heard/listened to. [mss]