I want to do some very basic editing of STEP files, e.g.: I need to do this sort of thing about a hundred times, so I'd rather learn how to fish than pay someone to do it, even if it's only a few $$ ...

There are dozens of file formats for word processing documents, database files, graphics, spreadsheets and so on. If a file was created in one application and you want to use it in another, you can ...