Most of the current exclusive-OR sum-of-products minimization algorithms use rule-based heuristics to transform an initial circuit description into a possibly compact form. This paper presents an enhanced minimization algorithm, MINT, introducing new transformations including rules operating on three product terms at a time. These multiple-product-term transformations prove to be an efficient extension of previously defined two-product-term operating rules. Additionally, new efficient procedures for the optimization based on the use of don't cares are introduced. The algorithm can simplify multiple-valued input two-valued multiple-output incompletely specified functions.