Original sentence: However many locomotives, particularly in the United States were built to Mallet's basic design but without employing compounding.Mallet's original patent specifies compound expansion.Purists consider only compound locomotives to be true Mallets.The term "Mallet" is generally applied to all locomotives built to the basic wheel arrangement specified in the patent
Edited sentence: Purists consider only compound locomotives to be true Mallets, but especially in the United States many non-compound ('simple') locomotives of a similar  pattern were built.Unfortunately no good name for this design ever emerged, and they tend to get called 'Mallets' nonetheless, or 'articulated' which is a little too non-specific