Portable Document Format (PDF)
Last updated at 6:10 pm UTC on 4 September 2017
An open standard
https://www.iso.org/standard/51502.html
ISO 32000-1:2008 specifies a digital form for representing electronic documents to enable users to exchange and view electronic documents independent of the environment in which they were created or the environment in which they are viewed or printed. It is intended for the developer of software that creates PDF files (conforming writers), software that reads existing PDF files and interprets their contents for display and interaction (conforming readers) and PDF products that read and/or write PDF files for a variety of other purposes (conforming products).
Squeak support
See SPDF
See also
http://christianhaider.de/dokuwiki/doku.php?id=pdf:pdf4smalltalk
https://freedesktop.org/wiki/Software/poppler/