The Block Rectangle function may be used to define a rectangular containment region for the other block functions to act upon. Once defined, the block may be further confined by specifying a restricted set of source layers using the Block Layers function.
Blocks can be represented by either a sparse fill region or an animated dashed perimeter. This is selectable from the General tab of Setup Options.
Animated perimeter
Sparse fill
A rectangular block is defined by selecting two corner points and a source reference point.