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As per this wikipedia article (see Fonts section), only pdf v1.6 and above is able to embed opentype fonts in the document.

Now the problem is that, my institution requires pdf /A-1b compliance which can be achieved through the pdfx package. The problem is that its documentation discourages the use of an explicit option that sets this document version.

For example, if I need pdf1.6, I could have simply passed the option pdf16 to the package. From the documentation of the package:

pdf16: use PDF 1.6, overriding the version specified by the applicable standard. This may produce a non-standard-conforming PDF file`

I am using libertinus open-type unicode fonts for my PhD thesis processed by luatex (TL 2018). The unix command pdfinfo says that the pdf version is only 1.5 which means the full open-type features are not present in the document.

I really wish to embed opentype fonts into the PDF whilst maintaining PDF A/1-b compliance. Can I achieve this somehow?

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  • Which open type features are you missing in pdf1.5? – Ulrike Fischer Aug 29 '18 at 18:41
  • @UlrikeFischer Well, all of the open-type features are missing in PDF 1.5. For instance, see this link (which supports the quote in the wikipedia link). As per this reference, "Direct embedding of OpenType fonts – these no longer have to be embedded as TrueType or Type 1 fonts." – Dr Krishnakumar Gopalakrishnan Aug 29 '18 at 18:45
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    Sure but are you missing anything concretly? Beside this: using 1.6. may give an non conforming pdf. A small test with a short document showed that you need to use at least \pdfvariable objcompresslevel=0 when setting the pdf version to 1.6. More complicated documents could use more features that should be in a A1-b pdf. – Ulrike Fischer Aug 29 '18 at 18:59
  • @UlrikeFischer I see. Hmm..... Perhaps I am better off using PDF/a-2 level of compliance. As per this wikipedia article, "Part 2 of the standard, published on June 20, 2011, addresses some of the new features added with versions 1.5, 1.6 and 1.7 of the PDF Reference. PDF/A-1 files will not necessarily conform to PDF/A-2, and PDF/A-2 compliant files will not necessarily conform to PDF/A-1. Part 2 of the PDF/A Standard is based on a PDF 1.7 (ISO 32000-1), rather than PDF 1.4 and offers a number of new features". My university simply says "PDF/A" – Dr Krishnakumar Gopalakrishnan Aug 29 '18 at 19:04
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    I have a hunch that most universities actually don't know what they are asking for when they say "PDF/A". Certainly at my institution the text reads as though the thought "we want a PDF - but what if people don't know what a PDF is or we get people claiming all sorts is a PDF if they just have a file extension .pdf, let's include this ISO standard to cover our bases legally" They don't even mention the conformance level. So the question is whether or not anyone will actually check anything (or would even know how to do that!) as long as the thing you hand in is obviously a PDF. – moewe Aug 29 '18 at 20:01
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The internal way LuaLaTeX handles fonts automatically leads to PDF/A-1 compatible files – so there is no problem. This minimal example does not throw a font related validation error in Acrobat DC Preflight for PDF/A-1b when processed in LuaLaTeX:

\documentclass{article}
\usepackage{libertinus-otf}
\begin{document}
Text $\sqrt{3}$
\end{document}

I hope it's not too late for your PhD.

*https://en.wikipedia.org/wiki/OpenType

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  • Also do you any reference that "PDF/A-1 requires TrueType"? As far as I know PDF/A-1 only requires the fonts to be embedded, so both TrueType and CFF should be fine. Actually your example demonstrated a CFF font. – Marcel Krüger Mar 30 '20 at 16:20
  • I did not buy the standard. But Wikipedia: PDF/A states OpenType is allowed only from PDF/A-2 on. And my example not only validates Preflight but also VeraPDF. – tanGIS Mar 30 '20 at 16:41
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    Yes, but that refers to OpenType, not CFF/PostScript. There are multiple ways to embed OpenType fonts into PDF files: The traditional way which is used by LuaTeX, XeTeX etc. and which is allowed in PDF/A-1 extracts the inner TrueType or CFF font and embeds that into the PDF directly. The other (not allowed) variant is that in newer PDF versions OpenType fonts can be embedded directly, without extracting the TrueType or CFF part first. This only works in PDF 1.6 and is therefore not allowed in PDF/A-1, but that isn't relevant for LuaTeX: LuaLaTeX doesn't use that format anyway. – Marcel Krüger Mar 30 '20 at 16:46
  • I adjusted the answer. – tanGIS Mar 30 '20 at 16:57

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