Base

The lower part of the shield. There is a dexter [H], middle [J] and sinister [I]  base. See Shieldpoints. A charge placed in the base of a shield is said to be in base, but any single charge when borne either at left or right, should be more particularly expressed, as in the dexter base point or in the sinister base point.

The base is also a charge being the width of a bar parted off from the lower part of the shield by a line horizontally drawn. The base as a charge is sometimes called base-bar or baste, but is better termed plain point to distinguish it from the points of the shield.  See plain point.

per baste bar was a terms used by early heralds expressive of the same kind of bearing, and divides the field barways at the base, of the width of the bar. See Leigh, Ferne, Randle Holme, and other early authors.