Interesting question that I can not find a direct answer too..... but also not sure how to search for the topic either. Background: I have a factory that makes both a consumer grade and an automotive grade component. The components ( both consumer and automotive grade ) are similar in construction and manufacturing process, but do have a few differences appropriate to the environment they are used in. The factory that makes these components is certified under both ISO and TS for these component's product categories specifically. The consumer grade component is less expensive than it automotive grade version and its production process is based mainly on the ISO standard. The automotive grade product is more expensive to cover product differences ( like to withstand high temperature, etc. ), the cost of the PPAP process and the cost of production using the more stringent TS standard. I have had a consumer customer audit this factory. The customer is non-Automotive and purchases 100% consumer grade parts. In the audit, the customer wanted to audit the consumer production line to the TS standard, under their understanding that a TS certified factory should use TS standard for all products, even if that product is not for the automotive market. Question: For a factory that has both TS and ISO certification for a given product category on its certification, is it formally required or stated somewhere that the factory must always use the TS standard in production for all products in a given category, even if the product made is a consumer grade product, not intended for automotive market? Any clarification is greatly appreciated.