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Re: Untagged PDF doc with table structure

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From: Andrew Kirkpatrick
Date: Feb 18, 2015 8:47AM

I'm not sure. My impression from discussions on this is that the big hit comes from the tagging process rather than storing the existing tags. If you don't have issues with documents of the same length that are tagged already then I don't think that you would with documents after the autotagging is complete.
AWK

-----Original Message-----
From: <EMAIL REMOVED> [mailto: <EMAIL REMOVED> ] On Behalf Of Jonathan C Cohn
Sent: Wednesday, February 18, 2015 7:42 AM
To: WebAIM Discussion List
Subject: Re: [WebAIM] Untagged PDF doc with table structure

Andrew,

Is the only reason to not auto-tag the entire document a time initial issue? I generally have based my decision on the amount of RAM available on my system. If the document is quite large, and one has is already using most of the active RAM, will tagging a 100+ page document cause slow page changes because of swapping?
Thanks,

> On Feb 18, 2015, at 09:36, Andrew Kirkpatrick < <EMAIL REMOVED> > wrote:
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> Jon is correct. When Acrobat opens an untagged document and there is a client that is using the accessibility API data running, Acrobat (or Reader) will add tags to the document. The result is the same as if an author used the "add tags" feature in Acrobat. You get Acrobat's best interpretation of what the tags should be. That will sometimes result in headings, well-formed tables, lists, and other structures. Authors who use this feature in Acrobat know that you generally need to fix some of the tags.
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> The result is that the document is tagged temporarily and assistive technologies recognize and use the information.
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> The dialogs that you see when opening PDF documents give you some information about what is going on. To understand better, here's my explanation.
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> In acrobat or Reader preferences there is a "Reading" category. There is a checkbox that is labeled "Confirm before tagging documents". If this is checked, then every time that Reader intends to tag an untagged document the "Reading an untagged document with assistive technology" dialog pops up and the user needs to confirm that this is what they'd like to do. If the user selects cancel then the document won't be tagged and the reading experience will be essentially non-existent.
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> If you elect to allow the tagging, there are other options as mentioned in one of the replies. I recommend using the "infer reading order from document" option.
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> There are other settings related to large documents and auto-tagging. Autotagging takes time, so if you open a very dense 600 page manual you may find that Reader takes a long time to do the tagging. It can, and we are always looking to improve the efficiency of this process. The option for the user is to indicate whether the autotagging should occur only on visible pages, on all pages in the document, or on all pages except if the document is "large". The user gets to define what large means - a user might find that their system is slow at this so sets the limit at 25 pages, or might set it higher if their system handles this process quickly. The down side of only tagging a few pages at a time is that if there are recognized structures on pages that haven't been tagged yet (e.g. a heading on page 51) the user can't use screen reader heading navigation to jump to it because the tags don't exist until the page is in view in the reader.
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> Hope this helps,
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> AWK
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> -----Original Message-----
> From: <EMAIL REMOVED>
> [mailto: <EMAIL REMOVED> ] On Behalf Of Lynn
> Holdsworth
> Sent: Wednesday, February 18, 2015 4:36 AM
> To: WebAIM Discussion List
> Subject: [WebAIM] Untagged PDF doc with table structure
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> Hi all,
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> Apologies if PDF accessibility is off topic. If so is there a list that covers this?
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> But if not ...
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> I open a PDF document, and Adobe Reader alerts me that it's untagged.
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> So I begin to peruse it using JAWS, and come across a table whose structure is robust enough for me to move around it using the JAWS table keystrokes.
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> Does this mean there *are* tags in the document after all? Or has Adobe Reader used heuristics to add tags to improve the doc's accessibility, since my settings flag up that I'm using a screenreader?
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> I tried to download a trial version of Acrobat Pro so as to examine the document structure, but the download assistant seems inaccessible.
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> Thanks as always, Lynn
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