WPD file format
This is a text document file format created in 1980 by Satellite Systems International for their WordPerfect word processing software. Several versions of Microsoft Word can open WPD. In 1997, the production of DOS and Macintosh versions of WordPerfect were stopped while the current owners, Corel, continued producing the Windows version. WordPerfect was still the most popular office suite until 2years ago. In 1994, it was acquired by Novell and by Corell in 1996.
WPD was created for only processing formatted text, that is, the files with formatted texts. This formatting information is stored via tags and recognized as codes by WordPerfect. So, errors in formatting are easily detected because the programs highlight texts to be formatted. Just like the DOC, WPD files embed information from other sources like databases, templates, or spreadsheets.