We use the TRBC market-based classification system. In this, companies are assigned an industry on the basis of the market they serve rather than the products or services they offer.
Market-based classification emphasises the usage of a product rather than the materials used for the manufacturing process because the performance of companies is tied to the market that they serve. Market based systems allow investors to group companies that share similar market characteristics.
In this example, catering services to airlines are considered airport services rather than restaurants because their financial performance is dependent on the market for airline services.