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"Equivalency" in UAAG/WCAG, Checkpoint 2.3

From: Hansen, Eric <ehansen@ets.org>
Date: Fri, 13 Oct 2000 19:25:08 -0400
To: "UA List (E-mail)" <w3c-wai-ua@w3.org>
Message-id: <B49B36B1086DD41187DC000077893CFB8B444B@rosnt46.ets.org>
Re: "Equivalency" in UAAG/WCAG, Checkpoint 2.3

Al,

In your memo entitled "Minority opinons (equivalency has no 'target,' only
'partners')" ([0]) you raised several important issues that deserve to be
addressed.

I hope that these responses are helpful. I will address the issues
individually.

- Eric

====

Question 1. Is the term "equivalent" the best term for expressing a
uni-directional relationship between pieces of content?

Response:

You have, in effect, posed the question as to whether the term "equivalent"
is the best way to express such a uni-directional relationship. 

In order to address this question, I want to start where I think (and hope)
that we can all agree. Specifically, I don't think I hear any disagreement
about whether the UAAG (29 September 2000) conception of equivalency is
uni-directional (asymmetrical). The concept of equivalent is summarized in
the following sentence from the definition of "Equivalent" in the glossary.

"In the context of this document, an equivalency relationship between two
pieces of content means that one piece -- the "equivalent" -- is able to
serve essentially the same function for a person with a disability (at least
insofar as is feasible, given the nature of the disability and the state of
technology) as the other piece -- the "equivalency target" -- does for a
person without any disability." (UAAG, 29 September 2000, definition of
'Equivalents (for content)')

Note that under this definition, just because content A is an equivalent for
content B does _not_ necessarily mean than content B is an equivalent for
content A. Thus, the relationship is uni-directional (asymmetrical) as
opposed to bi-directional (symmetrical).

Now let us get back to the question of whether the terms "equivalent",
"equivalency target", and "equivalency relationship" can make sense for such
a uni-directional relationship. 

Let us consider the following excerpts the range of meanings found in the
entry for "equivalent" in the on-line Merriam-Webster Dictionary [5]:

"1 : equal in force, amount, or value; also : equal in area or volume but
not admitting of superposition <a square equivalent to a triangle>"
"2 a : like in signification or import b : having logical equivalence
<equivalent statements>"
"3 : corresponding or virtually identical especially in effect or function"
"4 obsolete : equal in might or authority"
"5 : having the same chemical combining capacity <equivalent quantities of
two elements>"
"6 a : having the same solution set <equivalent equations> b : capable of
being placed in one-to-one correspondence <equivalent sets> c : related by
an equivalence relation"

Some have expressed concerns that the UAAG concept of equivalent does not
match meaning #1 ("equal in force, amount, or value"). Yet consider the
other meanings. For example, meaning #6b ("capable of being placed in
one-to-one correspondence") seems very compatible with our usage of the term
as does meaning #2b ("having logical equivalence <equivalent statements>").
Meaning #2a ("like in signification or import") and meaning #6c ("related by
an equivalence relation") appear related, but not as directly.

My conclusion from this review is that our usage of the term is well within
the acceptable range of meanings for the term "equivalent". 

It might be possible (or might have been possible) to find a different word,
other than "equivalent" that would convey the uni-directional nature of
"equivalent" and thereby avoid the sense of concern that we feel about the
fact that our usage of equivalent does not match perfectly meaning #1 of
equivalent ("equal in force, amount, or value").

In conclusion, I have no problem with trying to find words that better
express the uni-directionality of the relationship between an equivalency
target and its equivalent. But at the same time, I am not persuaded that our
current usage is seriously flawed.
 
====

Question 2. Is the UAAG conception of equivalency fundamentally different
from that expressed in WCAG?

Response:

You have indicated that the UAAG concept of equivalency is contrary to that
expressed in WCAG (1.0). You stated:

"The "equivalent vs. equivalency target" definitions in this volume are not
the same definition of "equivalent" as in math, English or the _WCAG_ and
the math, English and _WCAG_ sense is appropriate in this context, and the
usage currently in the draft is not." ([1], emphasis added)

Although you did not seem to elaborate on this particular issue, insofar as
I understand your concern, I disagree.

Ian is correct in his suggestion that in crafting language for the UAAG
definition of equivalent, I was trying to remain consistent with what is
found in WCAG 1.0 [2].

The WCAG 1.0 definition 'Equivalent' states:

"In the context of this document, the equivalent must fulfill essentially
the same function for the person with a disability (at least insofar as is
feasible, given the nature of the disability and the state of technology),
as the primary content does for the person without any disability." (WCAG
1.0, definition of 'Equivalent')

Please note that this definition, like that of the UAAG definition of
equivalent, is uni-directional. The basic changes that we have in UAAG is
that we give the relationship a name ("equivalency relationship") and that
instead of using the term 'primary content' we use the term 'equivalency
target'. I think that Ian would agree that the term 'primary content' has
long been a 'fuzzy' (ambiguous) term that we haven't felt entirely
comfortable with. I think that the working group is acquainted with my
efforts to find a good definition for the term 'primary content'. And when I
proposed the term 'equivalency target' [3], the working group accepted it
[4]. As noted in the minutes [4], working group members seemed to appreciate
its simplicity and that it neutralizes or eliminates some of the negative
connotations that seemed associated with some definitions of 'primary
content'. 

In conclusion, I find the UAAG concept and definition of equivalency
fundamentally in line with what is expressed in WCAG. Most to the point,
both the UAAG and WCAG conceptions of equivalent are uni-directional
(asymmetric) in their equivalency relationship.

====

3. Is the current UAAG conception of equivalency simply the
"primary/alternative" distinction but in different words?

Response:

You indicated that "The current language (in the 29 Sept. Draft) is just
primary/alternate content under new labels." I am reasonably certain that I
disagree. I would be more certain if I knew that we were agreed about the
meaning of the "primary/alternate" distinction. As I mentioned earlier in
this memo, the term "primary" has long been known to have some ambiguity in
it. And as you know, I struggled for quite a while trying to bring about
some consensus regarding the meaning of "primary content" ([6], [7], [8],
[9]) but ultimately failed [3].

Notwithstanding some uncertainty about what is or should be meant by the
term "primary content", I think I understand what you are referring to and
will try to respond on that basis.

I surmise that you think that the UAAG distinction "equivalency target
versus equivalent" is another name for the distinction "content intended for
people _without_ disabilities versus content intended for people _with_ any
disabilities". A number of people found the latter distinction troubling in
my discussion of "primary content"; in that context the distinction went
under different names, sometimes "primary content/secondary content" and
other times "primary content/alternative content". 

As I indicated in a recent telecon, I have revised some of my thinking about
the relevance and value of this distinction ([3], [4]). For the record, I
will say that I think a better name for the distinction might be "core
content" (intended for audience without any disabilities, plus any people
with disabilities who can benefit from it) and supplementary content
(intended for audience with disabilities who find the core content
inaccessible).

If this is what you meant when you indicated that "The current language (in
the 29 Sept. Draft) is just primary/alternate content under new labels" then
I disagree and will attempt to show how these distinctions are different. I
will say that I expected this concern would arise and have been looking
forward to the opportunity to clarify this point.

The idea I would like to get across this: The concept of equivalency as I
have been trying to articulate it is neutral_ as to whether any or both of
the two pieces of content -- equivalent or equivalency target -- are
intended for people with a certain disability status (e.g., with
disabilities versus without disabilities). This means, for example, that
there is nothing in the basic meaning of equivalent or equivalency target
that denotes that one is intended for people with disabilities and one is
for people without disabilities. 

This may seem surprising since the UAAG definition of equivalent, which
says:

"In the context of this document, an equivalency relationship between two
pieces of content means that one piece -- the "equivalent" -- is able to
serve essentially the same function for a person with a disability (at least
insofar as is feasible, given the nature of the disability and the state of
technology) as the other piece -- the "equivalency target" -- does for a
person without any disability." (UAAG, 29 September 2000, definition of
'Equivalents (for content)')

This definition makes clear reference to a person _with_ a disability at the
'equivalent' end of the relationship and a person _without_ a disability at
the 'equivalency target'. If so, then how can one then likewise affirm, as I
do, that my concept of equivalency "is _neutral_ as to whether any or both
of the two pieces of content -- equivalent or equivalency target -- are
intended for people with a certain disability status (e.g., with
disabilities versus without disabilities)"?

The answer is essentially this: Just because content X serves essentially
the same function for a person _with_ a disability and as content Y does for
a person _without_ a disability DOES NOT MEAN that the author intends
content X for persons _with_ disabilities and content Y for people _without_
disabilities. The author's intended audience for a piece of content is _not_
denoted by its status as an equivalent or as an equivalency target. That
intention, insofar as it is important, must be designated by another means
or, if necessary, guessed at. Let us consider an example of a Web-based
instructional module that is teaching about _captions_ for multimedia
presentations (movies, etc.) and that this instructional module is designed
for all audiences. The captions are a kind of equivalent, specifically a
text equivalent of the auditory track of the movie that is synchronized with
the visual and auditory tracks. My assertion is that even though the caption
text is a text equivalent for the auditory track of the movie, this does not
mean that the author intends those captions, in the context of that
instruction, specifically for people _with_ disabilities. Indeed, as we have
said, in this case the author intends the caption text for people _without_
disabilities (as well as people with disabilities who can benefit from
them). 

Thus, I disagree that "The current language (in the 29 Sept. Draft) is just
primary/alternate content under new labels." Personally I believe that the
ability for an author to indicate that he or she intends some piece of
content for persons with certain classes of disability. (I am confident that
in some applications, this capability will prove essential.) The importance
of this ability is increased by the fact that the distinction is between
equivalent and equivalency target is _not_ a vehicle for conveying such
information; in any given instance, one, or both, or none of the equivalent
and the equivalency target might be intended for people with disabilities.
On the other hand, the disability status of the intended audience was the
_defining_ characteristic of the primary/alternative (or primary/secondary)
distinction.

I will reexamine the language of the UAAG document and see if there is a way
that I can clarify this issue in the document. 

Thanks for giving me the opportunity to discuss this point.

====

Question 4. Should checkpoint 2.3 be altered to take in a greater variety of
relationships?

Response:

Judging from comments on the list, there seems to be quite a bit of interest
in expanding the scope of checkpoint 2.3.

I think that this is a very good point to bring up. Your suggestions have
helped me think through my concerns about things that don't fit into the
regular mold of equivalency relationships.

Here is my suggestion for checkpoint 2.3:

"2.3 Where multiple elements of content within a document are related by
_equivalency and similar relationships_, provide easy access to each element
among the related elements. This shall be done through at least one of the
following mechanisms: (1) allowing configuration to render one element
instead of other related elements; (2) allowing configuration to render more
than one of the related elements; (3) allowing the user to select a
displayed element and then inspect any of the other elements; (4) providing
a direct link to other related elements, just before or after a displayed
element in document order.
[Priority 1]"
"Note: For example, if an image in an HTML document has text equivalents,
provide access to them by (1) allowing configuration to replace one element
from among the image and its rendered equivalents;  (2) allowing
configuration to render an image plus one or more of its rendered
equivalents; (3) allowing the user to select a displayed image or equivalent
and then inspect any of the other elements; (4) providing a direct link to
other related elements (image or equivalent), just before or after a
displayed element in document order."
"Techniques for checkpoint 2.3"

Also, add the following to the definition of Equivalent or in a Note:

"_Equivalency and similar relationships_ include at least the following:
equivalency relationships; linearizations and summaries of tables;
expansions (of acronyms); abbreviations (of phrases); language translations;
titles, etc."  

Comment 1:

I used a "defined" term "element" rather than an undefined term "fragment";
provide the example; defined the "equivalency and similar relationships". 

Comment 2:

I presume that we don't need to mention that they only need to work with
what they can recognize.

Comment 3:

I suspect the definition of "Equivalency and similar relationships" needs
further work.


Below for comparison are (1) the old (29 September 2000) version of
checkpoint 2.3 and (2) Al Gilman's suggestion.

Old (29 September 2000):

2.3 Provide easy access to each equivalent and each equivalency target
through at least one of the following mechanisms: (1) allowing configuration
to render the equivalent instead of the equivalency target; (2) allowing
configuration to render the equivalent in addition to the equivalency
target; (3) allowing the user to select the equivalency target and then
inspect its equivalents; (4) providing a direct link to the equivalent in
content, just before or after the equivalency target in document order.
[Priority 1] 
Note: For example, if an image in an HTML document has text equivalents,
provide access to them (1) by replacing the image with the rendered
equivalents, (2) by rendering the equivalents near the image, (3) by
allowing select the image and then inspect its equivalents, or (4) by
allowing the user to follow readily available links to the equivalents. 
Techniques for checkpoint 2.3

Al's suggestion:

2.3 Where there are multiple fragments of content within a document which
are equivalent in the senses that they convey the same information, closely
or roughly; provide easy access to any equivalent among the range of
equivalents. 
This shall be done through at least one of the following mechanisms: (1)
allowing configuration to render one equivalent instead of another; (2)
allowing configuration to render more than one equivalent; (3) allowing the
user to a displayed equivalent and then inspect any equivalents of the
selected item; (4) providing a direct link to another (each other)
equivalent in content, just before or after a displayed equivalent in
document order.
[Priority 1]

REFERENCES:

[0] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000OctDec/0085.html
[1] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000OctDec/0086.html
[2] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000OctDec/0087.html
[3] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000JulSep/0429.html
[4] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000JulSep/0493.html
[5] http://www.m-w.com/cgi-bin/dictionary
[6] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000JulSep/0414.html
("Primary content -- OK as a "Fuzzy" Concept?")
[7] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000JulSep/0207.html
("Primary Content", etc. - Response to Ian Jacobs)
[8] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000JulSep/0184.html
("Primary Content", etc. - Corrected!)
[9] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000JulSep/0178.html
(""Primary Content", etc.")

<END OF MEMO>

===========================
Eric G. Hansen, Ph.D.
Development Scientist
Educational Testing Service
ETS 12-R
Princeton, NJ 08541
609-734-5615 (Voice)
E-mail: ehansen@ets.org
(W) 609-734-5615 (Voice)
FAX 609-734-1090
Received on Friday, 13 October 2000 19:27:09 GMT

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