This example generates a pattern of horizontal and vertical bars overlaid with two circular masks, revealing a cross-hatched grid within a circular window. The visualization uses D3 v6 to create SVG rectangles and mask elements, with `select` and `range` from the d3 library. Data is generated programmatically with a loop for horizontal bars and `range` for vertical bars, while masks combine white and black shapes to control visibility. The result demonstrates how SVG masks can create layered geometric compositions.