We have been sued because Calc is not creating ADA compliant PDF files. It seems like the items that are missed would be very simple to implement. I created a very simple spreadsheet that demonstrates and will attached. The following checks do not pass.
Primary Language (this works in Writer, but not Calc)
Tagged content (this is checked during PDF export, but seems not to work)
Tab Order (In this case, the form button was not pressed, so there isn't really a tab order. But there must be a PDF attribute that indicates this fact. When you perform this with Excel, this check is not flagged).
Attaching work files.
Created attachment 149738 [details]
Created attachment 149739 [details]
PDF as created by Calc
Created attachment 149740 [details]
Using Adobe Pro to check the resulting file.
Dave, please add info about your LibreOffice version from dialog Help->About
Tested on Version: 126.96.36.199.0+
Syncing now with 6.3 daily to see how it works.
Ok, downloaded 6.3 daily snapshot:
TinderBox: Linux-rpm_deb-x86_64@86-TDF, Branch:master, Time: 2019-03-03_20:19:18
And it had the same results. Three attributes seem not be written to the PDF from calc. Attaching shot of results from Adobe Pro.
Created attachment 149747 [details]
Results In Adobe Pro from Calc 6.3 (Alpha)
So no /Lang entry gets recorded into the PDF (suggested in WCAG 2.0's PDF16 technique ) believe we should at least pick up the language from OS locale, or from default LO template in use. But then we don't really handle additional language assignments in Calc needed to tag at individual table or even the cell level--i.e. bug 34142
Otherwise with current master/6.3.0alpha0+, on Export to PDF from Calc with either "Tagged PDF (add document structure)" or the "Archive PDF/A-1a (ISO 19005-1)" selections checked--confirm a lack of tags in PDF for the table headings and cell elements, and lack of tab and reading order for the tables of the sheet (as in WCAG 2.0's PDF3 technique ).
Testing with veraPDF and, Acrobat Pro DC--on Windows 10 with current NVDA screen reader.