Researchers agree that open standard file formats are less obsolete and more reliable than
proprietary formats.28 Close examination of the NISIS definition mentioned above reveals that
standard file formats are in reality not free, nor do they allow unrestricted access to resources.
The three file formats that ISO has announced (PDF/A, OOXML, and ODF) are proprietary and
sometimes costly. They also prohibit the purchase of access to a proprietary standard, although
there is an assumption that a standard should be free from legal and financial restrictions. The
ISO-announced file formats, in short, are only standard file formats, not open standard file formats