Xun occupies the southwest in the Earlier Heaven arrangement attributed to Fuxi, facing Zhen in the northeast. In the Later Heaven arrangement attributed to King Wen it moves to the southeast, which is where the compass schools and the classical commentaries place it.
The Later Heaven order follows the year rather than a symmetry, and the southeast is the turn from late spring into early summer, the point at which growth that began in the east is spreading. A trigram whose attributes are wind and wood, the gradual and penetrating influence, fits that stretch of the cycle better than it fits any cardinal point.
In the Later Heaven order Xun belongs to the phase Wood, shared with Zhen, and the pairing is worth noticing: Zhen is wood as the first upward thrust, Xun is wood as the slow lateral spread, and the phase covers both. From the Shuogua Xun takes the fowl among animals and the thigh among the parts of the body, the joint that carries the body forward without being what touches the ground. In the family scheme Xun is the eldest daughter, holding the first yin line at the bottom, exactly mirroring Zhen.
The mirroring is structural rather than decorative. Zhen and Xun are inversions of each other, and every correspondence they carry can be read as a pair.
Sources Fathoming the Cosmos and Ordering the World: The Yijing (I Ching, or Classic of Changes) and Its Evolution in ChinaRichard J. Smith with The I Ching, or Book of ChangesRichard Wilhelm (trans.); Cary F. Baynes (English trans.), The Five "Confucian" ClassicsMichael Nylan