Convert XLSX to PMD

As far as we know, the only way to produce .pmd spreadsheets from MS Excel sources (.xls, .xlsx) is to use PlanMaker. It appears the PMD format used in PlanMaker is not that well supported in other spreadsheet programs, perhaps with the exception of programs based on Ashmapoo software. However, as several more file types use pmd extension, it may be possible that some other xlsx to pmd conversion exists.