Acrobat v. CommonLook re: Pass/Fail & Tag Tree structural changes or Tags getting changed on Save?

[andreao7166925]

I've run a PDF through Acrobat DC for accessibility (not without some problems arising . . . but this seems to be a normal occurence, leaving me saving every few minutes), which passed, but the issue I've come across is that after sending on to others (I work for an educational organization which is getting increasingly tight on accessibility), info has come back to me saying there were problems that DIDN'T pass. I believe those folks passed it through CommonLook, so I did a search and came across this statement: "Acrobat doesn’t actually test against WCAG 2.0, PDF/UA" . . . is this true? I've seen things on Adobe's site that suggest otherwise, but I have to wonder which is accurate and why ADC Pro produces a pass report when CL checks the same PDF and does not?

Problems I've come across—like elements getting moved to a different location (under totally different tags which alters the proper nesting of parent/child tags, or sometimes merging several elements together under one tag when they were previously made separately tagged items, or DC Pro actually changing the tag I gave it to one that isn't accurate at all (<li>s changing to <p> tags), upon saving the doc and hopefully, the changes I've made. It's been frustrating to say the least, but I bow out of the process if I save and the nesting structure remains in tact but an <li> tag changes to <p>, with the reasoning that the content is readable and still technically correct (a paragraph), even if it's dumped the bullet denoting to a blind user that there is a list of items coming up. "They wil hopefully figure it out as long as the nesting remains and content is readable, and I can't risk saving again and having the whole tree structure change unexectedly again" being my logic. But if folks have never tried to make a PDF accessible and haven't experienced such issues first hand, it may look to them that I am lazy, careless, unprofessional! That's what bothers me most. If there's something I'm missing, or if anyone experiences this, I'm open to hearing your approach. Also, if there's input on CommonLook or maybe a combination of tools that are most reliable checking against WCAG 2.0, PDF/UA standards?

Thanks 🙂

AO

P.S. I have read other people having similar structure problems on here and made note to try some of the solutions, but sometimes my issue would be just slightly different. I know this is a lot of info and might be better placed elsewhere . . . apologies, but it's kind of an overall issue re: Acrobat.

[a_C_student · Accepted solution]

"Acrobat doesn’t actually test against WCAG 2.0, PDF/UA" . . . is this true?

Yep. The accessibility checker built into Acrobat Pro is not very thorough. It checks against a subset of WCAG.
The CommonLook PDF validator is much more thorough, tests against WCAG and/or PDF/UA, and is free. Unfortunately in my experience it gives too many false fails. 
Another choice is the PDF Accessibility Checker (PAC 3) from Access for All. It is free and very thorough in checking against PDF/UA. It does not claim to check against WCAG but as far as I know all WCAG criterea that can be auto-checked are also covered by PDF/UA.
My preference is Acrobat for a first-check and PAC 3 for final check. Gotta remember though that many WCAG and PDF/UA criterea can not be auto-checked but rather require careful, knowledgeable human inspection. PAC 3 includes a logical structure view and screen reader emulator that facilitate human inspection. 

Re. tags changing on thier own - would need to know more specifics or to look at an example document. It may be that these problems go away as you gain experience, or your PDFs may be possessed by evil poltergeists (yep, it happens).

[ls_rbls]

In which version of Acrobat DC is this happening?  Is it just happening with one One particular PDF or every PDF?

Can you tell if when a specific third-party content that uses javascript for predictive content is casuing the issue after it is embedded in your original document(s)? 

I suggest you refer to this for clarification of where Adobe Acrobat may fall responsible or not with the issue that you're describing: https://www.w3.org/TR/WCAG20-TECHS/pdf

Below I marked in bold the areas that I believe can answer your inquiry and help you pinpoint where the issue is really stemming from.

See specifically this part: 

"

PDF Technology Notes
Introduction

The Portable Document Format (PDF) is a file format for representing documents in a manner independent of the application software, hardware, and operating system used to create them, as well as of the output device on which they are to be displayed or printed. PDF files specify the appearance of pages in a document in a reliable, device-independent manner. The PDF specification was introduced by Adobe Systems in 1993 as a publicly available standard. In July 2008, PDF 1.7 became an ISO standard (ISO 32000-1) [ISO32000].

Of note for accessibility is PDF/UA (Universal Accessibility) which became an ISO Standard in July 2012, and was updated in 2014 (ISO 14289-1:2014 (See PDF/UA (ISO 14289-1:2014).) The scope of PDF/UA is not meant to be a techniques (how-to) specification, but rather a set of guidelines for creating more accessible PDF. The specification describes the required and prohibited components and the conditions governing their inclusion in or exclusion from a PDF file in order for the file to be available to the widest possible audience, including those with disabilities. The mechanisms for including the components in the PDF stream are left to the discretion of the individual developer, PDF generator, or PDF viewing agent. PDF/UA also specifies the rules governing the behavior for a conforming reader.

PDF Accessibility Support

PDF includes several features in support of accessibility of documents to users with disabilities. The core of this support lies in the ability to determine the logical order of content in a PDF document, independently of the content's appearance or layout, through logical structure and Tagged PDF. Applications can extract the content of a document for presentation to users with disabilities by traversing the structure hierarchy and presenting the contents of each node. For this reason, producers of PDF files must ensure that all information in a document is reachable by means of the structure hierarchy.

I would suggest that you reach out to this Adobe Community Professional:

 https://community.adobe.com/t5/user/viewprofilepage/user-id/1835976