Accessibility documentation says to use unavailable subset value

[taybin]

What subset should be used to enable PDF/UA? The documentation says

Pass the option subset: 'PDF/UA' when creating your PDFDocument (if you wish the PDF to be identified as PDF/UA-1).

But that is not a valid value, as of 0.20.2.

[blikblum]

Please open a PR

[taybin]

I'm not sure what the fix is. Is the documentation wrong or is the library type wrong, and if so can it be easily extended?

[blikblum]

Add a document option to set PDF/UA and update docs

[tevinch]

'PDF/UA' is the correct runtime value in 0.20.2: initSubset already handles it and calls initPDFUA().

I reproduced the TypeScript mismatch with @types/pdfkit@0.17.6: its PDFKit.Mixins.PDFSubsets union lists only PDF/A values. With TypeScript 7.0.2 in strict mode, the documented option gives TS2322. For these versions, this temporary assertion on the supported literal compiles:

import PDFDocument = require('pdfkit');

const doc = new PDFDocument({
  subset: 'PDF/UA' as PDFKit.Mixins.PDFSubsets,
  tagged: true,
  lang: 'en-US',
  displayTitle: true,
  info: { Title: 'Accessible document' },
});

The declaration needs to include 'PDF/UA'; the existing runtime does not need a new option for that value. The assertion should be removed once the types include it, and should not be applied to arbitrary strings.

I also compiled and ran a complete tagged-paragraph example against the published 0.20.2 package. With the upstream Roboto font fixture, the finished PDF contains the PDF/UA-1 metadata and passes veraPDF 1.30.2's UA-1 profile. That validates this small example; the constructor options alone do not make other content accessible.