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Re: A case for artifacting bullets in unordered lists in PDFs

for

From: McMorland, Gabriel
Date: Jul 23, 2013 11:05AM

bullets in lists tell readers where one list item ends and another begins. This is very important semantic information for screen reader users who cannot rely on visual layout. Or spacing.
I can't think of an example where it wouldn't be helpful to have bullets included.

-----Original Message-----
From: <EMAIL REMOVED> [mailto: <EMAIL REMOVED> ] On Behalf Of Jonathan Metz
Sent: Tuesday, July 23, 2013 12:59 PM
To: WebAIM Discussion List
Subject: Re: [WebAIM] A case for artifacting bullets in unordered lists in PDFs

Hi Olaf,

Thanks for responding.

>-characters used for bullets in bulleted lists (from my point of view)
>are not an accidental by-product of doing page layout / pagination
>(they exist also -on web pages, where no such layout / pagination
>happens) -by definition this implies that they cannot be artifacted
>just because they happen to be in front of list items


My reasoning comes from a discussion I had a while ago on LinkedIn about what to do with custom bullets in Links. It was suggested that if they provided no semantic meaning, Bullets should be hidden from screen readers. I guess the school of thought being that if it had numbers, it would be more important to listen to them. But I see yours (and others) point about how creating a Bullet for a list creates semantic context for what kind of list it is.

>
>- PDF and PDF/UA require that such bullet character is put inside a
><Lbl> tag

The problem is, PDF 1.7 never explicitly states that a <Lbl> tag is mandatory. The only language it provides is through the 'ListNumbering'
attribute (under Table 347), which says "Lbl elements (if present) contain arbitrary text not subject to any numbering scheme". I understand that ListNumbering is about what kind of L it is, but this was the only indication I could find where 32000 mentions the Lbl's presence. Why would it mention 'If Present' if it couldn't possibly also be 'Not Present'?
Could I use the ListNumbering to specify this is an unordered list instead in previous documents? Where would that have gone? I digress...


ISO 14289 only states "Lbl and LBody tags may be included". The Tech Imp guide mentions that these things should be hidden from view.

Whatever, I see your points and will change my recommendation regarding Bullets in PDFs.


>- on the content inside the Lbl (not on the Lbl, please).



If I change the properties in a content box, it affects the tag it resides in. Should I nest these inside <Span> then?

Again, thanks for the advice. I'll suggest otherwise from now on since I have real world examples of a request for bullets in a list. If there is a list without bullets, how would I provide the ListNumbering Attribute?

Thanks!
Jon




On 7/23/13 11:20 AM, "Olaf Drümmer" < <EMAIL REMOVED> > wrote:

>Hi Jonathan,
>
>Am 23 Jul 2013 um 16:21 schrieb Jonathan Metz
>< <EMAIL REMOVED> >:
>
>> Currently I¹m working with someone who insists that unordered lists
>>should have a <Lbl> in the tag tree if there is a graphic or glyph
>>representing the 'bullet' character. My approach to unordered lists
>>in PDFs is to artifact the bullet character.
>
>my take:
>
>- characters used for bullets in bulleted lists (from my point of view)
>are not an accidental by-product of doing page layout / pagination
>(they exist also on web pages, where no such layout / pagination
>happens)
>- by definition this implies that they cannot be artifacted just
>because they happen to be in front of list items
>- so if they are present, and as they might convey information, they
>have to be made accessible

>- PDF and PDF/UA require that such bullet character is put inside a
><Lbl> tag

>- in most documents the bullet character is a well defined character
>(the usual bullet character comes with a Unicode code point, U+2022,
>and that code point is not in the private use area); thus nothing extra
>(like applying an ActualText attribute) has to be done in such cases as
>the character can be pronounced as "bullet" by a screen reader (or the
>respective word in other languages)
>- there might be cases where the bullet point is something other than
>the usual bullet character; as long as that other character has a well
>defined Unicode code point outside the private use area, all is fine,
>no extra work necessary (you can actually check this if you use callas
>pdfGoHTML: if the bullet character looks the same as in PDF, the
>Unicode code point seems to work OK, if you see replacement characters,
>usually empty square characters, it is probably using a private use
>area code point (private use area - PUA - means that no predefined
>meaning is associated with code points in this PUA area), and in this
>case some extra work is necessary (see next list item [pun intended ;-) ]).
>- in some cases pictorials are used (or characters without well defined
>Unicode code point, or a Unicode code point from the private use area)
>- either a piece of vector graphic, an image, a non-Unicode character,
>or
>whatever: in such cases, one may have to use the ActualText (if the
>content of these pictorials is more like text, or maybe a bullet point
>drawn in a fancy or multi-colored way, but still looking like a bullet
>point) or Alt attribute (if the pictorials are more like images) on
>the content inside the Lbl (not on the Lbl, please).
>
>It will be up to assistive technology (AT) how to present the contents
>of the Lbl tag. I can understand why some users would want to turn off
>(at least some of the time) reading out / displaying the Lbl - but it
>must be possible, if configured accordingly, that access to Lbl is provided.
>
>HTH.
>
>Olaf
>
>
>>>messages to <EMAIL REMOVED>