Definition: Symmetric input-output table
A symmetric input-output table is a product by product or industry by industry matrix describing the domestic production processes and the transactions in products of the national economy in great detail. A symmetric input-output table rearranges both supply and use in a single table. There is one major conceptual difference between a symmetric input-output table and a combined supply and use table: in the supply and use table, the statistics relate products to industries, while in the symmetric input-output table the statistics relate products to products or industries to industries. So, in a symmetric input-output table either a product or an industry classification is employed for both rows and columns.
Eurostat, "European System of Accounts - ESA 1995", Office for Official Publications of the European Communities, Luxembourg, 1996