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Re: Character limit on alt-text in PDF?

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From: Chagnon | PubCom
Date: Jun 28, 2013 2:03PM


RE: Alt-text length. I was advised long about to keep it under 200
characters. Can't even begin to find where that recommendation came from.

RE: long descriptions in PDFs, this question has been asked a few times on
this list and never, in my opinion, satisfactorily answered.

WCAG doesn't acknowledge that PDFs exist. <grin>

We've developed some solutions that we think meet the intent of WCAG 2.0,
based on what WAI technique 1.1.1 recommends for websites
http://www.w3.org/WAI/WCAG20/quickref/#qr-text-equiv-all

1) For graphical charts and other graphics that illustrate statistical data:

- If the source document is available, add a table below the graphical chart
that contains the same data. We've found that our AT testers prefer this
solution because it gives them direct access to the data.

- If you can't change the source document but are stuck working with just
the PDF, add a blank page at the end of the PDF and put the table there. In
some cases, it can be helpful to also have a paragraph of text to describe
or analyze the data, what a LONGDESC would do. Hyperlink from the graphic to
the back page, and then hyperlink a return to the original page. Messy to
create, but it works fine for AT-users.

2) For other situations:

- If you can edit the original source document, work a narrative description
into the body text that describes the graphic's data. Something like "in the
bar chart below, sales increased to $2,000 in May, a 100% increase from
April which were $1,000."

- If you can't, the "back of the PDF" method above will work for this, too.

-Bevi Chagnon
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-----Original Message-----
From: <EMAIL REMOVED>
[mailto: <EMAIL REMOVED> ] On Behalf Of McMorland,
Gabriel
Sent: Friday, June 28, 2013 2:43 PM
To: <EMAIL REMOVED>
Subject: [WebAIM] Character limit on alt-text in PDF?

Is there a character limit on the alt-text for images in PDFs?
If not, then how long is too long?

Also, where do you usually put long descriptions for complex images in PDFs
hosted on a website? If it was HTML I could use longdesc, but I'm not sure
where to put them with the PDFs used in our online courses.

Thanks for your thoughts,
Gabe
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