Home Glossary Performance specification Glossary Performance specification By Deviation Check Editorial Team. Short answer A spec that states the result a product must achieve, such as a rating, capacity, or tolerance, rather than naming a specific product. The sub may use any product that meets the stated performance. Related terms Prescriptive specificationProprietary specification Browse the full glossary, the CSI division guides, or learn how submittal review works. Then run a review. View this page as Markdown for LLMs and note-taking.