ISO 32000, in 2008, and does not require any royalties for its implementation. The PDF specification how to capture a signature from a pdf provides for encryption and digital signatures, file attachments and metadata to enable workflows requiring these features.
Adobe Systems made the PDF specification available free of charge in 1993. ISO Committee of volunteer industry experts. Adobe that are necessary to make, use, sell, and distribute PDF compliant implementations. These proprietary technologies are not standardized and their specification is published only on Adobe’s website.
Many of them are also not supported by popular third-party implementations of PDF. ISO 32000-2 does not include any proprietary technologies as normative references. Any files, graphics, or fonts to which the document refers also are collected. Then, everything is compressed to a single file. Comments may contain 8-bit characters.