ye.

(Y)EH that one / aquél (M) This particle has alternate forms YEH~EH (Cf.88r) and is a constituent of several types of construction. As a free element it serves as a minimal third person pronoun and as a grammatical referent standing for a whole proposition (as, it, what, and that do in various English constructions). This same particle seems to be a constituent of the Nahuatl pronominal system, NEH, NEHHUĀ-TL, etc., being derived from the personal prefixes plus EH; N-EH, N-EH-HUĀ-TL ‘I,’ etc. A third use of (Y)EH is as a sort of anchor at the end of particle clusters; NŌCUĒLYEH ‘on the other hand,’ QUĒNOCYEH ‘all the more,’ MĀNOCEH < MĀ NO ZO (Y)EH ‘nor even, if only,’ CUIXAHZOYEH ‘I don’t know whether.’ These clusters are sometimes written spaced as separate words and sometimes solid with internal assimilation, but the entitive sense of (Y)EH remains plausible in even the most lexicalized of them.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 338.