δ-box

Noun

 * 1)  A k-cell which is a Cartesian product of half-closed intervals which are closed at their infima and open at their suprema, and such that the infimum of each interval is the coordinate of a given point (called "the corner" of the δ-box), and the length (i.e., measure) of each interval is equal to (the given value) δ.

Usage notes
The "δ-box with corner at a" can be denoted symbolically as Q(a; δ). The 'δ' in "δ-box" can be subject without notice to substitution by any numerical expression, with the hyphen being replaced by a space.