Proprietary data file formats are file formats that rely on dedicated, licensed softwares and/or systems. These file formats are often copyrighted, patented, or have other restrictions placed on them, and often require a fee or a paid-for software to open. These file formats are usually discouraged in research projects, especially those with intentions to share with a wider public(s) and audience. This is distinct from open data formats. Some examples of it include .xslx, .doc, and .3ds.
- Library of Congress Recommended Formats Statement
- Stanford University's best practices for file formats