category-set-mnemonicscategory-set-mnemonics is a built-in function in `
C source code'. (category-set-mnemonics CATEGORY-SET) Return a string containing mnemonics of the categories in CATEGORY-SET. CATEGORY-SET is a bool-vector, and the categories "in" it are those that are indexes where t occurs in the bool-vector. The return value is a string containing those same categories.