The NPA file extension is associated with Weibull++ software. It contains data used by Weibull++. This entry was marked obsolete. Programs which support NPA files are Weibull++.
To solve problems with NPA files: Associate the NPA extension with the correct app. Update software that should open NPA files. Only the current version supports the latest format.
Windows file names have two parts: the name and a 3-4 character extension defining the file type. In expenses.xlsx, expenses is the name and xlsx is the extension. Windows allows variable length names, permitting multiple dots and suffixes.