PlanMaker spreadsheets (.pmd) can be exported as Excel spreadsheets (.xls) using the default File ► Save as function in the program. This is pretty much the only direct pmd to xls conversion we know of.
However, as pmd file suffix is used for several different file types, it may be possible that also other .pmd files can be somehow exported as Excel spreadsheets. If you are looking for something particular, please leave as a message in the discussion below.
Updated: February 10, 2017