XLM is an old format for Microsoft Excel spreadsheets with macros. It has been superceded by XLSM, a new XML-based format. The new macro format is based on Visual Basic for Applications (VBA), but the old format was different. The old format was used through Excel 4.0, could be run but not created in 5.0, and is not supported in later versions. It was mostly supported in Windows versions, with some limited support in some Mac versions.