What defines a "commercial pattern" in fashion design?

A commercial pattern in fashion design refers specifically to a set of sewing instructions available for public purchase. These patterns typically include detailed templates for cutting fabric as well as guidelines for assembling garments, enabling individuals of varying skill levels to create clothing at home or in a workshop setting. Commercial patterns are widely produced by various brands and are accessible to consumers through retail channels, making them a popular resource for both amateur and experienced sewists looking to replicate specific styles or designs.

The other options do not accurately describe a commercial pattern: a unique design for a specific client would relate more to custom fashion design, styles exclusive to high-end fashion houses indicate exclusivity rather than mass production, and a rare fabric pattern refers to fabric choices rather than the patterns themselves used in garment construction.