Exact masks and source seams
Abstract
Ascending physical reserve masks
For a<=b<=c and a<c, the V mask is the nonnegative rounded quotient of e2-3A by 2e1. Its exact dyadic cases give e2<=S2<=2e2-A and S2<e2+2e1, including b=c and a=b,c=a+1. The W mask and low U release follow the literal constructor. Their capacity and reserve bounds retain the adjacent T=2R family, the a=2 boundaries, and the T=R equality face.