pdf-association
7.3.10 Introduced new incorrect text in 2020 revision
The Note in 7.3.10 states:
(2020) Any object outside of an object stream (see 7.5.7, "Object streams") can consist solely of an object reference. PDF syntax thus permits chains of such objects.
However, (a) this text is in dispute as whether it is indeed a correct interpretation of PDF syntax processing and (b) is of a more normative nature and should not be in a note (if we decide to leave it in).
Adobe PDF 1.5: p.78: "Note: It is illegal for a compressed object to consist of nothing but an indirect reference; for example, 3 0 R."
@lrosenthol to do some PDF archeology and discuss in next PDF TWG
Should make a 2nd example using something that is not a /Length key as some PDF sw don't process /Length keys.
This and other related/interlinked issues (#194 #199 #201 #208 ) are being discussed in the "Securing PDF" DG of ISO TC 171 SC 2 WG 8 and will be labelled as "Parked" here in GitHub until such time as a set of solutions can be proposed.