The sole is the underlying part of a foot or shoe, that portion touching the ground. The type of sole found in period armory is the shoe sole, which has its toe to chief by default; it’s found in the canting arms (dial. Italian söra) of de Sori, mid-15th C. [Triv 325], and illustrated in Bossewell, 1572 [III.17].
In Society armory, we find an example of the sole of a human foot. While this charge is found in mundane armory in the arms of Voet [Woodward 207], it has not been dated to period. Like the shoe sole, the human foot sole has its toes to chief by default.
Percival de la Rocque bears as a badge: A shoe sole per pale purpure and gules.
Mat of Forth Castle bears as a badge: The sole of a human foot vert.