Assertion: format | /r/HasProperty | proprietary
Facets:
Source sentences:
text: As an extension explicitly for Microsoft’s proprietary document processor, the format was also proprietary: Word was the only program that officially supported DOC files until Microsoft opened the specification in 2006, after which it was reverse-engineered.
text: However these formats are either not widely supported, or are proprietary.
text: Some formats are proprietary and may not be widely supported where you live, such as KML (the HieBook eBook format), RB, (Rocket) and WOLF (HanLin).