The ISO released the 2.0 version of the specification that replaces the 1.7 standard.
"Although it is an open standard, one major difference compared with prior versions of PDF is that ISO now holds the copyright to the PDF specification and thus PDF 2.0 is not freely downloadable." [0]
It looks like DMCA requests are being issued to anyone that hosted the old specification, even open source projects [1].
[0] https://www.pdfa.org/resource/iso-32000-pdf/ [1] https://github.com/Hopding/pdf-lib#git-history-rewrite
> This page was updated on 23 March 2022 as many direct links to legacy PDF specifications on adobe.com were broken. Many links now reference the Wayback Machine internet archive and thus may be slow.
It's possible they're reworking their CMS and that causes files to be moved (breaking links everywhere). Microsoft loves doing that with their developer blogs.
Off topic, but man is that document hard to use as a reference. Ironically, I wish they would publish it as HTML broken down by chapter and section.
(I have used that document a lot to write a custom PDF generator and parser in Java, using a downloaded copy)
Maybe one of the side effects of this is that people only continue writing against PDF 1.7.
Maybe they want to sell it :)
It's still available at this Adobe URL: https://opensource.adobe.com/dc-acrobat-sdk-docs/standards/p... "As distributed by Adobe after adoption as ISO 32000-1:2008, with permission of ISO." [0]
Not to mention ISO unsurprisingly host it, which I would also consider authoritative: https://www.iso.org/obp/ui/#iso:std:iso:32000:-1:ed-1:v1:en
[0] https://www.loc.gov/preservation/digital/formats/fdd/fdd0002...