validation fails

[arnoudo]

Thank you for developing a shell program with form processing functionality!

The attached file testform.pdf was exported from testform.odt in LibreOffice Writer 7.5.3.2 (latest). The command "pdfcpu form list testform.pdf" returns the following error.

pdfcpu: validateNameEntry: dict=pagesDict entry=Tabs invalid type types.StringLiteral

As a sanity check, I made another file testform2.pdf by adding form fields with Adobe Acrobat Pro 9 (latest version I have). The command "pdfcpu form list testform2.pdf" succeeds. So apparently, the issue is with the PDF file exported from LibreOffice.

OS: Windows 10 Enterprise 22H2 64-bits (19045.2846)
pdfcpu: v0.4.0 dev
build : 2023-03-01T00:15:26Z
commit: 7ff654b

I hope this report may be helpful in the development of your code. Let me know if you need any other information or tests. This is the first time I submit a bug (on Github or anywhere) so apologies if this does not follow the intended format.

testform.odt
testform.pdf
testform2.pdf

[hhrutter]

Your file does not validate since the page attribute Tab is expected to be a name object.
We will have to extend relaxed validation.

Always ensure your input files pass validation before processing them:
pdfcpu validate input.pdf

[petervwyatt]

I found the error and reported to LibreOffice: https://bugs.documentfoundation.org/show_bug.cgi?id=155228

[asciim0]

@petervwyatt - quick question, if i may. do you consider this pdf error critical?

[petervwyatt]

The page object /Tabs entry is used for defining the navigation order of annotations on a page. In the case of LibreOffice they define it to be in logical structure order (/S) - I assume because they are writing out Tagged PDF and logical structure. The comment a few lines above the line in question also mentions PDF/UA-1 (ISO 14289-1) which requires /Tab to be /S - so without this correction LibreOffice PDFs will not be compliant to PDF/UA-1!

If we ignore compliance to PDF/UA-1, then if a page has no annotation then it is not critical. But if the page has more than 1 annotation and especially if the PDF is read by end users with disabilities who rely on assistive technology then the /Tabs entry is very important for meaningful navigation of annotations. That is why it is a mandated requirement in PDF/UA-1!

[asciim0]

thank you very much for that explanation!