x1 = tai1 is a constellation of stars x2 = tar1 (set, quantity, region), according to standard x3.
x2 may also be a specified apparent region (two-dimensional projection) of the sky (as seen from/by a specific perspective or from specific location at a specific time) or a region (three-dimensional region) of the universe, and everything within them; x3 can specify which of these meaning options is meant, the authority determining whether it is a constellation or an asterism or which is defining the specified region, and the location and timing of at/from which the determination of the regions shape or contents is made by the observer (specify frame of reference). Cf. so'o, tarci, tarmi, tartai, tarso'imei, tarci'e, tarboi, cacryra'o.