A traceability matrix is a document, usually in the form of a table, used to assist in determining the completeness of a relationship by correlating any two baselined documents using a many-to-many relationship comparison. It is often used with high-level requirements and detailed requirements of the product to the matching parts of high-level design, detailed design, test plan, and test cases.
See the Sample Traceability Matrix
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Ref: https://en.wikipedia.org/wiki/Traceability_matrix