The clear open space between parallel wires (e.g., 50mm x 100mm or 2" x 2").

Impact on Load: It's not just about preventing items from falling; it's about structural density. A smaller aperture means more wires per square foot. More wires distribute the load across a greater number of support points, reducing stress on individual strands.
The Interaction: A deck with a large aperture (e.g., 100x100mm) relies heavily on the thickness of the wire. A deck with a small aperture (e.g., 25x25mm) gains significant rigidity from the grid density itself, even with slightly thinner wire.
Safety Factor: Smaller apertures provide better protection against small debris falling but may restrict airflow slightly more than larger grids.
link:https://www.safetyshelves.com/wire-products/wire-mesh-decking/waterfall-mesh-deck.html