PDF with HTML5 and CSS - Build fails with cross reference and accessibility or archiving mode

[InspectorSpacetime]

Using Oxygen 28 and Windows 11 (same happens also with Oxygen 27):

If a DITA topic contains cross references and the pdf.accessibility or pdf.archiving.mode parameters are used, the build fails with the error message: [CH] Error com.oxygenxml.chemistry.d.fb "FOP stage failed: For PDF/UA-1, all fonts, even the base 14 fonts, have to be embedded! Offending font: /Helvetica-Oblique"

Setting the args.css.param.show-onpage-lbl parameter to no makes the build run OK, so I suppose the problem is that the build is trying to use and embed Helvetica Oblique for the "on page" part of the output. And since that font is not shipped with Windows (don't know about Macs), the build fails as designed. Of course there are easy CSS workarounds, but I suppose the build should work out of the box?

[julien_lacour]

Hello,

The "base 14 fonts" mentioned in the error message refers to PDF Standard fonts list, which can be seen here.
The problem is actually related to the pdf.accessibility parameter. When generating PDF/UA-1 files, these fonts must also be declared in the CSS stylesheets. By default, the PDF viewer uses them to render portions of text that do not have a custom font specified.
You should either cover all text with your custom font or declare these fonts as well, for more information check our user guide.

Regards,
Julien