Other file formats
Some historical documentations may use the DOC filename extension for plain-text file format. The DOC
filename extension was also used in historical versions of WordPerfect for its proprietary format.
Some software applications use the name "DOC" in combination with other words (such as the name of
software manufacturer) for different file formats. As an example, on the Palm OS, DOC is shorthand for
PalmDoc, a completely unrelated format (commonly using PDB filename extension) used to encode text
files such as ebooks.