This
document
provides
supporting
information
for
the
User
Agent
Accessibility
Guidelines
(UAAG)
2.0
for
designing
user
agents
that
lower
barriers
to
Web
accessibility
for
people
with
disabilities.
User
agents
include
browsers
and
other
types
of
software
that
retrieve
and
render
Web
content
.
A
user
agent
that
conforms
to
these
guidelines
will
promote
accessibility
through
its
own
user
interface
and
through
other
internal
facilities,
including
its
ability
to
communicate
with
other
technologies
(especially
assistive
technologies
).
Furthermore,
all
users,
not
just
users
with
disabilities,
should
find
conforming
user
agents
to
be
more
usable.
In
addition
to
helping
developers
of
browsers
and
media
players,
this
document
will
also
benefit
developers
of
assistive
technologies
because
it
explains
what
types
of
information
and
control
an
assistive
technology
may
expect
from
a
conforming
user
agent.
This
document
provides
explanation
of
the
intent
of
UAAG
2.0
success
criteria,
examples
of
implementation
of
the
guidelines,
best
practice
recommendations
and
additional
resources
for
the
guideline.
The
"User
Agent
Accessibility
Guidelines
2.0"
(
UAAG
2.0)
is
part
of
a
series
of
accessibility
guidelines
published
by
the
W3C
Web
Accessibility
Initiative
(
WAI
).
May
be
Superseded
This
section
describes
the
status
of
this
document
at
the
time
of
its
publication.
Other
documents
may
supersede
this
document.
A
list
of
current
W3C
publications
and
the
latest
revision
of
this
technical
report
can
be
found
in
the
W3C
technical
reports
index
at
http://www.w3.org/TR/.
Editor's
Draft
of
UAAG
2.0
This
document
is
the
internal
working
draft
used
by
the
UAWG
and
is
updated
continuously
and
without
notice.
This
document
has
no
formal
standing
within
W3C.
Please
consult
the
group's
home
page
and
the
W3C
technical
reports
index
for
information
about
the
latest
publications
by
this
group.
Web
Accessibility
Initiative
This
document
has
been
produced
as
part
of
the
W3C
Web
Accessibility
Initiative
(WAI).
The
goals
of
the
User
Agent
Working
Group
(UAWG)
are
discussed
in
the
Working
Group
charter
.
The
UAWG
is
part
of
the
WAI
Technical
Activity
.
No
Endorsement
Publication
as
a
Working
Draft
does
not
imply
endorsement
by
the
W3C
Membership.
This
is
a
draft
document
and
may
be
updated,
replaced
or
obsoleted
by
other
documents
at
any
time.
It
is
inappropriate
to
cite
this
document
as
other
than
work
in
progress.
Patents
This
document
was
produced
by
a
group
operating
under
the
5
February
2004
W3C
Patent
Policy
.
The
group
does
not
expect
this
document
to
become
a
W3C
Recommendation.
W3C
maintains
a
public
list
of
any
patent
disclosures
made
in
connection
with
the
deliverables
of
the
group;
that
page
also
includes
instructions
for
disclosing
a
patent.
An
individual
who
has
actual
knowledge
of
a
patent
which
the
individual
believes
contains
Essential
Claim(s)
must
disclose
the
information
in
accordance
with
section
6
of
the
W3C
Patent
Policy
.
A
user
agent
is
any
software
that
retrieves,
renders
and
facilitates
end-user
interaction
with
Web
content.
Users
interacting
with
a
web
browser
may
do
so
using
one
or
more
input
methods
including
keyboard,
mouse,
speech,
touch,
and
gesture.
It's
critical
that
each
user
be
free
to
use
whatever
input
method
or
combination
of
methods
works
best
for
a
given
situation.
Therefore
every
potential
user
task
must
be
accessible
via
modality
independent
controls
that
any
input
technology
can
access.
For
instance,
if
a
user
can't
use
or
doesn't
have
access
to
a
mouse,
but
can
use
and
access
a
keyboard,
the
keyboard
can
call
a
modality
independent
control
to
activate
an
OnMouseOver
event.
What
qualifies
as
a
User
Agent?
The
These
guidelines
employ
the
following
tests
can
be
used
to
determine
if
software
qualifies
as
a
user
agent
for
the
purposes
of
these
guidelines.
It
agent.
UAAG
2.0
divides
potential
user
agents
into
Primary
Agents
(the
traditional
"browser"),
Extensions
and
Plug-ins,
and
Web-based
User
Agents.
-
platform-based
application
-
extension
or
plug-in
-
web-based
application
If
the
following
three
conditions
are
met
met,
then
it
is
a
Primary
User
Agent
and
Must
Conform
to
UAAG:
platform-based
application:
-
If
it
It
is
a
standalone
application;
application,
and
-
If
it
It
interprets
any
w3c
specified
language;
W3C-specified
language,
and
-
If
it
It
provides
a
user
interface
or
interprets
either
a
procedural
or
declarative
language
that
may
be
used
to
provide
a
user
interface.
interface
If
the
following
two
conditions
are
met
then
it
is
a
User
Agent
Extension
an
extension
or
Plug-In
and
Must
Conform
to
UAAG:
plug-in:
-
If
it
It
is
launched
by,
or
extends
the
functionality
of,
of
a
Primary
User
Agent;
platform-based
application,
and
-
If
post-launch
Post-launch
user
interaction
either
becomes
part
of,
is
included
in,
or
is
within
the
bounds
of,
of
the
Primary
User
Agent.
platform-based
application
If
the
following
three
conditions
are
met
then
it
is
a
Web-Based
User
Agent
and
Must
Conform
to
UAAG:
an
web-based
application:
-
If
the
The
user
interface
is
generated
by
the
interpretation
of
either
a
procedural
or
declarative
language;
and
-
If
this
interpretation
The
user
interface
is
by
a
Primary
User
Agent,
User
Agent
Extension
or
Plug-In;
embedded
in
an
application
that
renders
web
content,
and
-
If
user
User
interaction
is
not
passed
to
and
from
the
Primary
User
Agent,
User
Agent
Extension
controlled
by
a
procedural
or
Plug-In,
declarative
language,
or
if
user
interaction
does
not
modify
the
Document
Object
Model
of
its
containing
document.
Relationship
to
the
Authoring
Tool
Accessibility
Guidelines
(ATAG)
2.0
While
it
is
convenient
common
to
think
of
user
agents
retrieving
and
rendering
web
content
for
one
group
of
people
(end-users)
that
was
previously
authored
by
another
group
(authors),
user
agents
are
also
frequently
involved
with
the
process
of
authoring
content.
For
these
cases,
it
is
important
for
user
agent
developers
to
consider
the
application
of
another
W3C-WAI
Recommendation,
the
Authoring
Tool
Accessibility
Guidelines
(ATAG).
ATAG
(currently
2.0
is
in
draft)
provides
guidance
to
the
developers
of
tools
regarding
the
accessibility
of
authoring
interfaces
to
authors
(ATAG
2.0
Part
A)
and
ways
in
which
all
authors
can
be
supported
in
producing
accessible
web
content
(ATAG
2.0
Part
B).
The
Role
of
User
Agents
in
Web
Authoring
The
following
is
a
list
of
several
ways
in
which
user
agents
are
commonly
involved
in
web
content
authoring
and
the
relationship
between
UAAG
2.0
and
ATAG
2.0.
-
Preview
tool:
As
authors
edit
web
content,
they
too
l:
Authors
often
preview
their
work
in
user
agents
to
test
how
the
content
will
be
appear
and
operate.
ATAG
2.0
includes
a
special
exception
when
"Previews"
previews
are
implemented
with
pre-existing
user
agents,
so
there
are
no
additional
requirements
on
user
agent
developers
in
this
case.
-
Checking
tool:
tool
:
Authors
often
make
use
of
user
agent
error
panels
(e.g.
HTML
validity,
JavaScript
errors,
etc.)
errors)
during
authoring.
ATAG
2.0
Part
A
would
apply,
applies,
but
likely
would
may
not
include
any
additional
accessibility
requirements
beyond
what
is
in
the
UAAG
2.0.
2.0
success
criteria.
If
a
user
agent
includes
an
"accessibility
checker",
then
the
developer
should
consult
checker
implementation
guidance
in
ATAG
2.0
Part
B.
-
Edit
modes:
modes
:
Some
user
agents
include
a
mode
in
which
where
the
user
can
edit
and
save
changes
to
the
web
content,
modifying
the
experience
of
other
users.
In
this
mode,
the
user
agent
is
acting
as
an
authoring
tool
and
all
of
ATAG
2.0
would
apply.
applies.
-
Automatic
content
changes:
changes
:
Some
user
agents
(and/or
user
agent
plug-ins)
or
plug-ins
may
automatically
make
changes
to
the
change
retrieved
web
content
before
it
is
it's
rendered.
This
functionality
is
not
considered
an
authoring
tool
because
the
changes
are
made
to
the
user's
own
experience,
not
the
experience
of
other
users.
-
Providing
a
platform
for
web-based
authoring
tools:
tools
:
Many
web
applications
serve
as
authoring
tools
and
they
make
use
of
user
agent
features
in
order
to
deliver
their
functionality
(e.g.,
undo
text
entry,
adjust
font
size
of
the
authoring
tool
user
interface
etc.)
-
User
agent
developers
should
consult
ATAG
2.0
to
understand
the
ways
in
which
web-based
authoring
tools
can
depend
on
user
agent
features.
UAAG
2.0
Guidelines
The
success
criteria
and
applicability
notes
in
this
section
are
normative
.
Guideline
summaries
are
informative.
PRINCIPLE
1
-
Ensure
that
the
user
interface
and
rendered
content
are
perceivable
Implementing
Guideline
1.1
-
Provide
access
to
alternative
content.
@@
721
Summary
:
The
user
can
easily
determine
which
pieces
of
content
have
alternatives
such
as
alt
text
or
longdesc
and
choose
to
render
that
alternative
(1.1.1).
The
user
can
also
choose
at
least
one
alternative
such
as
alt
text
to
be
always
displayed
(1.1.2),
but
it's
recommended
that
users
also
be
able
to
specify
a
cascade
(1.1.4),
such
as
alt
text
if
it's
there,
otherwise
longdesc,
otherwise
filename,
etc.
The
users
can
choose
to
be
notified
(e.g.
by
an
icon)
when
unrendered
alternative
content
is
present.
(1.1.2)
1.1.1
Identify
Presence
of
Unrendered
Render
Alternative
Content
[was
1.1.3]
:
For
any
content
element,
the
user
can
choose
to
render
any
types
of
alternative
content
that
are
present.
(Level
A)
##
DONE
28
March
2012
-
Intent
of
Success
Criterion
1.1.1:
When
the
author
provides
alternative
content,
it
Alternative
content
is
wasted
if
users
cannot
find
it.
The
user
agent
should
make
the
presence
of
alternative
content
evident
to
the
user.
Users
should
not
have
to
hunt
and
examine
every
time
to
see
if
it
includes
such
content,
because
such
searching
can
be
time-consuming,
especially
for
users
whose
disability
makes
input
difficult,
tiring,
or
painful.
The
user
should
be
able
to
easily
identify
which
items
have
alternative
content,
rather
than
being
merely
informed
that
alternative
content
is
somewhere
in
the
view.
-
Examples
of
Success
Criterion
1.1.1:
-
Tinan
has
repetitive
strain
injuries
and
seeks
to
limit
scrolling.
The
user
agent
renders
distinct
visual
icons
in
proximity
of
content
that
has
short
text
alternatives,
long
descriptions,
and
captions.
If
the
icon
forces
the
text
to
extend
beyond
a
fixed
size
container
the
user
agent
uses
global
preference
settings
to
determine
whether
to
expand
the
container,
provide
scroll
bars,
or
truncate
the
content.
-
Aosa
is
blind.
When
rendering
a
Web
page
using
synthesized
speech,
the
user
agent
generates
an
audible
tone
to
signify
that
the
word
being
read
is
an
acronym,
and
Aosa
can
press
the
*
key
to
hear
the
expansion.
When
the
phrase
being
read
is
the
Alt
text
for
an
image,
another
tone
indicates
that
Aosa
can
press
+
to
hear
the
longdesc.
long
description.
-
A
button
Brin
is
deaf.
The
video
player
she
is
using
has
a
button
displayed
beneath
the
playing
video
to
indicate
that
indicates
that
captions
are
available
and
to
let
available.
She
clicks
the
user
button
to
toggle
their
display.
the
captions
on
so
she
can
understand
the
video.
-
Related
Resources
for
Success
Criterion
1.1.1:
-
(Refer
to
the
SC
about
handling
layout/reflow
options.)
None
1.1.2
Configurable
Alternative
Content
Defaults
[was
1.1.1]
:
For
each
type
of
non-text
content,
the
user
can
specify
a
type
of
alternative
content
that,
if
present,
will
be
rendered
by
default.
(Level
AA)
##
DONE
28
March
2012
-
Intent
of
Success
Criterion
1.1.2:
When
the
author
provides
alternative
content,
it
Alternative
content
is
wasted
if
the
user
agent
doesn't
render
it
for
users
who
need
it.
Default
alternative
content
is
a
global
option
because
it
is
an
unreasonable
burden
for
users
to
change
the
rendering
options
every
time
they
visit
a
new
page.
-
Examples
of
Success
Criterion
1.1.2:
-
Sally
is
blind.
In
the
browser's
preferences
dialog
box,
Sally
specifies
that
she
wants
alt
text
displayed
in
place
of
images,
and
that
the
document
should
reflow
to
allow
the
entire
alt
text
to
be
displayed
rather
than
truncated.
-
Ben
has
low
vision.
In
the
browser's
preferences
dialog
box,
Ben
he
chooses
to
always
display
the
alternative
("fallback")
content
for
embedded
objects,
such
as
videos.
-
Brin
is
deaf.
She
toggles
a
menu
item
which
turns
on
the
display
of
all
captions
for
video
and
audio
content.
-
Related
Resources
for
Success
Criterion
1.1.2:
1.1.3
Display
of
Time-Based
Media
Alternatives:
For
recognized
on-screen
alternatives
for
time-based
media
(e.g.
captions,
sign
language
video),
the
following
are
all
true:
(Level
AA)
##
DONE
2
August
2012
-
Do
Not
Obscure
Primary
Media:
not
obscure
primary
media:
The
user
can
specify
that
the
display
of
displaying
media
alternatives
does
not
doesn't
obscure
the
primary
time-based
media;
and
-
Do
Not
Obscure
Controls:
not
obscure
controls:
The
user
can
specify
that
the
display
of
displaying
media
alternatives
does
not
doesn't
obscure
recognized
controls
for
the
primary
time-based
media;
and
-
Configurable
Text:
Recognized
text:
The
user
can
configure
recognized
text
within
media
alternatives
(e.g.
captions)
can
be
configured
in
conformance
with
1.4.1.
1.4.1
.
Note:
Depending
on
the
screen
area
available,
the
display
of
the
primary
time-based
media
may
need
to
be
reduced
in
size
to
meet
this
requirement.
-
Intent
of
Success
Criterion
1.1.3
[was
2.11.11]
:
Users
who
require
or
can
benefit
from
alternative
media
tracks
in
video
or
audio
may
not
find
that
the
default
or
authored
position
and
size
of
those
tracks
to
be
is
usable.
Enabling
the
user
to
move
and
scale
any
displayed
alternate
media
tracks
(e.g.
captions)
allows
for
the
displayed
content
to
be
positioned
and
sized
to
meet
the
needs
of
the
user.
-
Examples
of
Success
Criterion
1.1.3:
-
Justin
has
low
vision
and
works
in
a
noisy
environment
that
makes
it
difficult
to
listen
to
instructional
videos.
When
he
enlarges
the
text
of
the
captions
to
a
viewable
size,
they
block
most
of
the
video
image.
Justin
selects
an
option
that
displays
the
caption
track
in
a
separate
window,
which
he
positions
below
the
video
image
so
the
captions
do
not
don't
block
the
video
image.
-
Jaime
is
deaf
and
is
taking
courses
from
on
online
university.
She
prefers
to
utilize
use
ASL
if
it
is
available
for
online
media,
and
a
current
media.
A
course
she
is
taking
offers
both
captions
and
a
signing
avatar
for
the
recorded
lectures.
The
default
size
of
the
avatar
window
is
small,
making
it
difficult
to
follow
the
signing.
The
avatar
also
overlays
a
significant
part
of
the
lecture
video.
Jaime
drags
the
avatar
out
of
the
video
and
enlarges
it,
so
that
both
they
are
equally
sized
and
side
by
side.
side
and
equally
sized.
-
Related
Resources
for
Success
Criterion
1.1.3:
1.1.3
[old]
Indicate
Unrendered
Alternative
Content:
##
DONE
28
March
2012
##
Deleted
4
June
2012
1.1.4
Default
Rendering
of
Alternative
Content
(Enhanced):
For
each
type
of
non-text
content,
the
user
can
specify
the
cascade
order
in
which
to
render
different
types
of
alternative
content
when
preferred
types
are
not
present.
(Level
AAA)
##
DONE
28
March
2012
-
Intent
of
Success
Criterion
1.1.4:
For
a
given
piece
of
non-text
content
the
author
may
have
provided
provide
one
or
several
more
alternatives.
For
example,
an
image
may
have
different
versions
based
on
resolution,
‘alt
text’
(@alt)
or
a
link
to
a
long
description
(@longdesc).
A
video
may
have
bandwidth
alternatives,
caption
files
in
different
languages,
and
audio
descriptions
in
different
languages.
Users
can
choose
which
item(s)
to
render
by
default,
and
specify
the
order
of
the
cascade
of
alternatives
to
be
rendered
if
the
author
did
not
provide
a
type
of
alternative.
provided
multiple
alternatives.
-
Examples
of
Success
Criterion
1.1.4:
-
Mary
has
a
learning
disability.
She
finds
looking
at
images
on
a
webpage
very
distracting.
Mary
would
like
to
see
all
images
rendered
in
the
following
order.
order:
First,
for
images
with
long
descriptions
have
descriptions,
render
the
long
description
rendered
in
place
of
the
image.
If
the
long
description
does
not
exist,
she
wants
render
the
‘alt
text’
to
be
rendered.
text’.
If
neither
is
available,
Mary
wants
render
the
file
name
rendered.
name.
Added
functionality
would
allow
Mary
to
right
click
(context
menu)
on
an
image
to
list
and
select
the
rendering
preferred
order
of
the
available
alternatives
(thumbnail,
original
size,
full
screen,
low
resolution,
high
resolution,
alt
text,
long
description,
file
name)
name).
-
Juan
is
hard
of
hearing.
He
always
wants
to
always
see
video
on
the
page.
Also,
Juan
would
like
wants
to
use
the
Spanish
language
track
used
if
available,
along
with
and
Spanish
captions
as
a
default.
If
these
are
not
available,
he
wants
to
see
the
video
with
English
audio
and
captions.
If
no
captions
are
available
available,
Juan
wants
the
video
and
with
English
audio.
Added
functionality
would
allow
Juan
to
right
click
(context
menu)
on
an
video
to
list
and
select
the
rendering
preferred
order
of
the
available
alternatives
(still
image,
caption
languages,
audio
languages,
audio-description
languages)
languages).
-
Related
Resources
for
Success
Criterion
1.1.4:
1.1.5
Size
and
Position
of
Time-Based
Media
Alternatives:
The
user
can
configure
recognized
on-screen
alternatives
for
time-based
media
(e.g.
captions,
sign
language
video)
as
follows:
(Level
AAA)
-
Resize:
The
user
can
resize
the
media
alternatives
up
to
the
size
of
the
user
agent's
viewport.
-
Reposition:
The
user
can
reposition
the
media
alternatives
to
at
least
above,
below,
to
the
right,
to
the
left,
and
overlapping
the
primary
time-based
media.
Note
1:
Depending
on
the
screen
area
available,
the
display
of
the
primary
time-based
media
may
need
to
be
reduced
in
size
or
hidden
to
meet
this
requirement.
Note
2:
Implementation
may
involve
displaying
media
alternatives
in
a
separate
window,
but
this
is
not
required.
##
DONE
2
August
2012
and
IER
on
16
August
-
Intent
of
Success
Criterion
1.1.5:
Users
may
want
to
reposition
the
alternative
so
they
can
be
placed
in
close
proximity
to
the
most
important
portion
of
the
main
media,
to
make
it
easier
media
to
watch
both
at
reduce
the
same
time.
visual
scanning
distance
between
them.
For
example
example,
if
the
video
frequently
includes
on-screen
text
near
the
top
of
the
video
then
the
captions
will
be
easier
to
read
if
they
are
located
above
the
video.
-
Examples
of
Success
Criterion
1.1.5:
-
Maximilian
will
adjust
adjusts
the
position
of
his
captions
depending
on
what
he's
watching.
When
watching
a
sporting
event
with
a
dashboard
displaying
statistics
at
the
top,
he
positions
the
captions
immediately
above
the
top
so
the
captions
are
close
to
the
statistics.
However,
when
he
watches
a
movie,
he
typically
positions
the
captions
so
that
they
overlap
the
video
frame
near
the
bottom.
When
he's
watching
he
watches
financial
news
with
a
stock
ticker
along
the
bottom,
he
moves
the
captions
to
be
immediately
below
the
ticker.
-
When
Tom
is
watching
watches
narrow-aspect
video
on
a
wides-aspect
screen,
he
moves
the
window
displaying
sign
language
interpretation
to
the
side,
allowing
the
primary
video
to
take
up
the
entire
height
of
the
screen
without
the
interpretation
getting
in
the
way.
-
Raymond
only
has
one
hand,
so
he
functioning
hand.
He
positions
captions
so
that
they're
not
covered
by
the
hand
he's
using
to
hold
his
tablet.
-
Related
Resources
for
Success
Criterion
1.1.5:
Implementing
Guideline
1.2
-
Repair
missing
content.
Summary
:
The
user
can
request
useful
alternative
content
when
the
author
fails
to
provide
it.
For
example,
showing
metadata
in
place
of
missing
or
empty
(1.2.1)
alt
text.
The
user
can
ask
the
browser
to
predict
missing
structural
information,
such
as
field
labels,
table
headings
or
section
headings
(1.2.2).
1.2.1
Support
Repair
by
Assistive
Technologies:
If
text
alternatives
for
non-text
content
are
missing
or
empty
then
both
of
the
following
are
true:
(Level
A)
-
(a)
the
user
agent
does
not
attempt
to
repair
the
text
alternatives
with
text
values
that
would
are
also
be
available
to
assistive
technologies.
-
(b)
the
user
agent
makes
metadata
related
to
the
non-text
content
available
programmatically
(and
not
via
fields
reserved
for
text
alternatives).
##
DONE
19
April
-
Intent
of
Success
Criterion
1.2.1:
When
alternative
content
is
missing,
it
is
sometimes
useful
for
users
to
have
access
to
alternative
information,
such
as
the
filename.
Users
need
to
control
the
flow
of
this
information,
because
an
uncontrolled
flow
can
be
distracting
and
time-consuming.
This
is
particularly
important
for
users
with
some
disabilities,
who
may
not
be
able
to
can't
use
some
forms
of
content
(e.g.
images)
or
may
even
need
to
avoid
some
forms
of
content
(e.g.
animations)
and
therefore
choose
to
replace
them
with
alternative
content.
Users
need
to
control
the
flow
of
the
content
when
this
information
is
added,
because
in
some
cases
cases
truncating
the
content
to
fit
its
container
will
may
make
the
document
unusable
(e.g.
if
important
information
becomes
hidden),
while
in
hidden).
In
other
cases
cases,
expanding
the
container
will
make
the
document
unusable
(e.g.
when
important
cues
no
longer
line
up
correctly).
Because
the
definition
for
Note
that
repair
text
is
only
required
for
alternative
content
required
by
the
specification
for
images.
For
example,
it
would
not
require
generating
transcripts
the
user
agent
to
generate
a
transcript
of
audio
using
speech
recognition,
for
example.
recognition.
-
Examples
of
Success
Criterion
1.2.1:
-
Ray
is
blind
and
counts
on
alternative
text
descriptions
for
images.
There
is
an
image
in
web
content
that
does
not
have
alternative
text
provided.
The
browser
displays
the
string
'(image
canoe.png)',
which
includes
the
file
name
because
that
is
the
only
available
information
about
the
image.
-
Bintu
is
deaf
and
relies
on
captions
to
replace
audio.
A
video
does
not
have
captions.
Bintu
selects
a
caption
button,
button
for
a
video
she
wants
to
watch,
and
is
informed
that
no
captions
exist.
The
player
then
analyzes
the
video
soundtrack
and
provides
speech
to
text
speech-to-text
translation
served
as
captions.
Note
:
this
is
an
advanced
example,
not
a
requirement.
-
Related
Resources
for
Success
Criterion
1.2.1:
1.2.2
Repair
Missing
Structure:
The
user
can
specify
whether
or
not
the
user
agent
should
attempt
to
insert
the
following
types
of
structural
markup
on
the
basis
of
author-specified
presentation
attributes
(i.e.
(e.g..
position
and
appearance):
(Level
AAA)
##
DONE
19
April
&
IER
done
on
2
August
2012
-
(a)
Labels
-
(b)
Headers
(i.e.
(e.g.
heading
markup,
table
headers)
-
Intent
of
Success
Criterion
1.2.2:
When
an
author
has
neglected
neglects
to
provide
labels
and/or
headers
as
necessary
for
accessibility,
the
user
agent
can,
in
some
cases,
can
sometimes
use
heuristics
to
determine
potential
labels
and/or
headers
from
presentation
attributes.
Once
potential
headings
and/or
labels
have
been
identified,
the
user
agent
can
proceed
(e.g.
with
communication
via
platform
accessibility
services)
as
if
the
relationship
was
defined
in
the
markup.
The
user
must
have
the
option
to
can
specify
whether
the
heuristics
should
be
applied
because
some
users
will
want
to
experience
the
content
as
the
author
provided
it,
for
example
it
(e.g.
to
perform
evaluations
or
when
they
find
that
heuristics
occasionally
fail.
fail).
-
Examples
of
Success
Criterion
1.2.2:
-
George
uses
speech
input.
When
content
markup
includes
a
checkbox
without
a
specified
label,
the
user
agent
detects
that
a
static
text
component
is
positioned
immediately
to
the
right
of
the
checkbox
and
no
other
static
text
components
are
nearby.
The
nearby
text
is
treated
as
the
label.
This
enables
George
to
toggle
the
checkbox
by
speaking
its
name.
-
Maria
uses
a
screen
reader.
When
a
table
lacks
marked
up
header
rows,
the
user
agent
gives
her
the
option
to
have
the
first
row
treated
as
the
table
header
row.
-
Li
uses
a
scanning
keyboard
and
makes
use
of
the
user
agent's
outline
view
to
more
efficiently
navigate
web
pages.
The
content
markup
(in
English)
includes
instances
of
static
text
that
differ
from
surrounding
text
due
to
(a)
being
because
they
are
sentence
fragments
and
(b)
being
styled
with
a
larger
font,
bold
weight
font
and
additional
spacing.
bold
weight.
The
instances
are
treated
as
headings
as
therefore
appear
in
the
outline
view,
enabling
Li
to
more
efficiently
navigate
to
them.
-
Related
Resources
for
Success
Criterion
1.2.2:
Implementing
Guideline
1.3
-
Provide
highlighting
for
selection,
keyboard
focus,
enabled
elements,
visited
links.
Summary
:
The
user
can
visually
distinguish
selected,
focused,
and
enabled
items,
and
recently
visited
links
(1.3.1),
with
a
choice
of
highighting
options
that
at
least
include
foreground
and
background
colors,
and
border
color
and
thickness
(1.3.2).
1.3.1
Highlighted
Items:
The
user
can
specify
that
the
following
classes
be
highlighted
so
that
each
is
uniquely
distinguished:
(Level
A)
##
DONE
5
April
2012
##
DONE
4
June
2012
-
(a)
selection
-
(b)
active
keyboard
focus
(indicated
by
focus
cursors
and/or
text
cursors)
-
(c)
recognized
enabled
input
elements
(distinguished
from
disabled
elements)
-
(d)
elements
with
alternative
content
-
(e)
recently
visited
links
-
Intent
of
Success
Criterion
1.3.1:
Users
need
to
be
able
to
easily
discover
web
content
they
can
interact
with.
One
effective
way
to
do
this
is
to
highlight
enabled
elements
and
links
(including
recently
visited
links).
They
also
need
to
know
where
they
are
working,
which
is
enabled
by
highlighting
Highlighted
selection
and
content
focus.On
focus
lets
people
who
use
keyboard,
gesture
and
speech
input
know
where
they
working.
On
some
pages
controls
may
be
difficult
to
discern
amid
a
large
amount
of
other
content,
or
may
be
styled
in
ways
that
make
them
so
the
controls
are
difficult
to
distinguish
from
other
content.
This
can
be
particularly
difficult
for
people
with
visual
impairments,
who
may
not
be
able
to
easily
distinguish
visual
differences
that
may
be
subtle
or
obvious
to
users
with
average
vision.
This
can
also
be
difficult
for
people
visual
differences.
People
with
some
cognitive
impairments,
who
impairments
may
have
difficulty
distinguishing
between
items
with
similar
or
non-standard
appearance.
The
ability
to
have
Visually
distinguishing
these
items
visually
distinguished
can
greatly
help
reduce
reduces
the
amount
of
time
or
number
of
commands
these
groups
require
to
examine
a
page.
Note
:
In
addition
to
these
required
categories,
it
is
recommended
that
user
agents
also
allow
the
user
to
highlight
the
active
viewport,
even
when
it
is
a
frame
or
similar
within
the
active
window.
This
makes
it
much
easier
for
the
user
to
visually
locate
the
active
focus.
Note
:
Platform
conventions
will
dictate
whether
or
not
an
inactive
keyboard
focus
(keyboard
focus
in
an
inactive
viewport)
viewport
is
visually
indicated
by
an
inactive
cursor.
Note
:
the
definition
of
visited
and
unvisited
links
is
up
to
the
user
agent.
In
some
cases
it
might
Visited
links
may
be
links
visited
during
the
current
session,
session
or
in
other
cases
links
visited
in
the
browser's
history
until
that
is
cleared.
history.
-
Examples
of
Success
Criterion
1.3.1:
-
Jerry
is
a
has
low
vision
user.
vision.
He
goes
to
a
website
that
uses
styles
to
override
visited
link
color.
He
wants
to
know
what
links
have
yet
to
be
explored.
The
user
agent
provides
a
dialog
box
for
setting
overrides
to
author-selected
link
colors.
Jerry
uses
the
dialog
box
to
override
the
author
styles
so
visited
links
are
indicated.
-
Jerry
goes
to
a
website
with
CSS
styles
that
removes
remove
the
content
focus
outline.
The
user
agent
provides
a
dialog
box
for
setting
overrides
to
the
author's
CSS
focus
outline
declaration.
Jerry
uses
the
dialog
box
to
display
the
content
focus
outline
so
he
tell
where
the
focus
is
on
the
page.
-
Binh
gets
easily
frustrated
when
he
cannot
locate
the
buttons
and
links
on
a
page,
usually
because
they
page.
This
happens
when
buttons
and
links
don't
have
the
standard
appearance
he's
used
to.
By
turning
The
user
agent
provides
a
dialog
box
for
setting
overrides
to
author-selected
link
colors.
Binh
turns
on
the
option
to
have
all
links
appear
in
bright
purple,
and
all
push
buttons
and
the
like
drawn
with
a
bright
purple
border,
border
so
he
can
easily
scan
the
page
and
find
the
items
he's
looking
for.
-
Related
Resources
for
Success
Criterion
1.3.1:
1.3.2
Highlighting
Options:
When
highlighting
classes
specified
by
1.3.1
Highlighted
Items
and
1.3.3
Highlighted
Input
Controls
,
the
user
can
specify
highlighting
options
that
include
at
least:
(Level
A)
##
DONE
12
April
2012
-
(a)
foreground
colors
,
-
(b)
background
colors
,
and
-
(c)
borders
(configurable
color,
style,
and
thickness)
-
Intent
of
Success
Criterion
1.3.2:
A
low
Low
vision
user
needs
users
and
users
with
some
cognitive
disabilities
need
control
over
what
visual
properties
work
best
for
highlighting.
to
meet
their
individual
needs.
These
include
foreground
colors,
background
colors,
and
visual
borders
(with
the
same
configurable
range
as
the
operating
environment's
conventional
selection
utilities)
-
Examples
of
Success
Criterion
1.3.2:
-
A
Alex
has
low
vision
wants
to
know
where
the
text
boxes
are
vision.
He
sometimes
has
difficulty
distinguishing
fields
on
a
web
form.
forms.
The
user
wants
agent
provides
a
dialog
box
allowing
the
user
to
set
override
any
author
settings.
He
chooses
to
have
all
form
fields
displayed
with
a
yellow
background
and
outlined
with
a
thick
black
border
around
all
text
boxes.
border.
-
Marcy
has
a
cognitive
disorder
that
makes
it
difficult
to
stay
focused
on
the
task
she
wants
to
accomplish.
The
user
agent
provides
a
dialog
box
allowing
the
user
to
override
any
author
settings.
Alex
has
low
vision
and
sometimes
has
difficulty
distinguishing
the
fields
on
web
forms.
He
She
chooses
to
have
all
form
fields
displayed
with
a
yellow
background
and
outlined
with
a
thick
black
border.
-
Related
Resources
for
Success
Criterion
1.3.2:
Implementing
Guideline
1.4
-
Provide
text
configuration.
Summary
:
The
user
can
control
text
font,
color,
and
size
(1.4.1),
including
whether
all
text
should
be
the
shown
the
same
size
(1.4.2).
1.4.1
Configure
Rendered
Text:
The
user
can
globally
set
any
or
all
of
the
following
characteristics
of
visually
rendered
text
content,
overriding
any
specified
by
the
author
or
user
agent
defaults:
(Level
A)
##
DONE
TPAC
-
(a)
text
scale
(i.e.
the
(the
general
size
of
text)
,
-
(b)
font
family
,
-
(c)
text
color
(i.e.
foreground
(foreground
and
background),
background)
-
(d)
line
spacing
,
and
-
(e)
character
spacing.
spacing
-
Intent
of
Success
Criterion
1.4.1:
Users
need
to
able
to
access
a
wide
range
of
font
sizes,
styles,
colors,
and
other
attributes
in
order
to
find
the
combination
that
works
best
for
their
particular
needs.
For
example,
some
users
want
to
increase
font
size
to
make
text
more
legible,
while
other
users
want
to
reduce
the
font
size
to
decrease
the
need
to
scroll
the
content.
In
providing
these
preferences,
it
is
important
to
avoid
making
assumptions.
For
example,
some
users
want
may
increase
font
size
to
make
text
more
legible,
while
other
users
may
reduce
the
font
size
to
decrease
the
need
to
scroll
the
content.
-
Examples
of
Success
Criterion
1.4.1:
-
Lee
has
low
vision
from
albinism
and
has
difficulty
with
screen
resolution
and
brightness.
She
chooses
to
have
all
text
displayed
in
Palatino
font,
with
white
text
on
a
black
background,
and
at
least
16
points
tall.
The
serif
Palatino
font
has
character
spacing
that
resolves
better
for
her
vision,
while
the
white
on
black
reduces
glare
and
the
larger
size
allows
her
to
distinguish
fine
detail
more
clearly.
-
Tomas
has
extremely
low
vision
and
chooses
to
have
his
Lee
uses
a
browser
display
all
text
the
same
size,
and
sets
that
size
as
large
as
he
can
without
making
the
letters
too
tall
for
his
screen.
He
chooses
not
to
have
headings
be
proportionately
larger
than
normal
text
because
on
her
mobile
phone
that
would
make
them
taller
than
his
screen
and
so
unreadable.
Browser
A
supports
only
3
font
sizes:
Small,
Medium,
small,
medium,
and
Large.
Lee,
who
has
low
vision,
large.
Lee
needs
to
use
a
font
size
of
16
pt,
which
is
between
the
medium
and
large
sizes.
Browser
A
provides
The
mobile
phone
settings
provide
an
option
to
override
the
3
font
sizes
with
the
operating
system
font
range,
so
that
Lee
can
select
the
16
pt
font
size
she
needs.
-
Mike
has
a
reading
disability.
A
web
site
uses
a
fancy
script
font
for
the
headings
that
he
cannot
understand.
He
chooses
to
have
all
text
displayed
in
a
plain
font
that
he
can
read.
-
Related
Resources
for
Success
Criterion
1.4.1:
1.4.2
Preserving
Size
Distinctions:
The
user
can
specify
whether
or
not
distinctions
in
the
size
of
rendered
text
are
preserved
when
that
text
is
rescaled
(e.g.
headers
continue
to
be
larger
than
body
text).
(Level
A)
##
DONE
TPAC
-
Intent
of
Success
Criterion
1.4.2:
The
relative
size
of
text
provides
visual
cues
that
help
in
understanding
and
navigating
web
content
and
because
some
content.
Some
content
may
be
authored
in
a
way
that
would
make
makes
it
difficult
or
impossible
to
understand
when
if
font
distinctions
were
hidden.
For
example,
hidden,
such
as
headlines
that
are
in
a
larger
font
than
the
body
text.
Users
It's
important
that
users
who
set
preferences
need
to
enlarge
or
reduce
the
text
size
need
be
able
to
have
preserve
these
visual
cues
preserved.
cues.
It
is
also
important
that
magnification
users
who
find
that
text
size
distinction
greatly
increases
scrolling
and
fatigue
be
able
to
display
all
text
at
the
same
size.
-
Examples
of
Success
Criterion
1.4.2:
-
Lee
has
low
vision.
She
finds
text
easiest
to
read
at
16
pt
Palatino,
but
can
Palatino
and
chooses
to
have
her
browser
display
all
body
text
in
the
Palatino
font
and
at
least
16
pt
in
size.
Palatino.
She
needs
the
headlines
to
scale
proportionally
(e.g.
24
pt)
in
order
to
preserve
headline
prominence.
-
Tomas
has
low
vision
and
uses
a
screen
magnifier.
He
chooses
to
have
his
browser
display
all
text
the
same
size,
and
sets
that
size
as
large
as
he
can
without
making
the
letters
too
tall
for
his
screen.
Tomas
chooses
not
to
have
headings
be
proportionately
larger
than
normal
text
because
that
would
make
them
taller
than
his
screen
and
so
unreadable.
-
Related
Resources
for
Success
Criterion
1.4.2:
Implementing
Guideline
1.5
-
Provide
volume
configuration.
Summary
:
The
user
can
adjust
the
volume
of
each
audio
track
relative
to
the
global
volume
level
(1.5.1).
1.5.1
Global
Volume:
The
user
can
independently
adjust
the
volume
of
all
audio
tracks
,
relative
to
the
global
volume
level
set
through
operating
environment
mechanisms.
(Level
A)
##
DONE
3
May
2012
-
Intent
of
Success
Criterion
1.5.1:
User
agents
can
render
audio
tracks
from
a
variety
sources,
and
in
some
cases,
multiple
audio
tracks
may
be
present
on
a
single
page.
Users
should
be
able
to
globally
set
the
volume
of
audio
tracks,
rather
than
having
to
adjust
the
volume
of
each
audio
track
being
played.
-
Examples
of
Success
Criterion
1.5.1:
-
An
operating
system
provides
a
master
audio
volume
control
that
applies
to
all
audio
tracks
rendered
within
the
environment,
including
the
user
agent.
The
user
may
define
a
default
volume
level
through
a
preferences
dialog
that
is
retained
across
sessions.
-
A
user
encounters
a
page
with
two
advertisements
and
one
video
which
begins
playback
on
page
load
complete.
A
global
mute
command,
supported
via
a
mute
key
on
the
user's
keyboard,
allows
the
user
to
immediately
silence
the
playing
audio
tracks.
-
Related
Resources
for
Success
Criterion
1.5.1: