The textcase package \MakeTextUppercase and \MakeTextLowercase are similar to the standard \MakeUppercase and \MakeLowercase, but they do not change the case of any sections of mathematics within the argument. Improvements from Donald Arseneau mean that \label, \ref and \cite also work within the argument of these commands, without the symbolic `key name' being incorrectly uppercased. In current LaTeX this package is obsolete. You can use the standard \MakeUppercase and \MakeLowercase, but it defines legacy names \MakeTextUppercase and \MakeTextLowercase.