Creating accessible PDF forms
For a PDF form to be accessible,
it be created as a tagged document. The goal is to ensure that all
fields are placed in the logical structure within the tag tree and that
they have appropriate text descriptors using tool tips or captions.
Design tips for creating accessible PDF forms
These tips will help
you create accessible forms for Acrobat and Adobe Reader:
Circle, line, and rectangle objects are not tagged in
PDF forms. These objects add no useful information for a user with
vision impairment or disabilities. Screen readers will not read
any information for these objects.
Do not set the Speak Order Precedence to None for field objects.
If you do, Acrobat will cause the screen reader to say “MSAA data
prompt not available” when the user tabs into the field, even if
the field is read-only.
Subforms are useful for organizing related objects and provide
a logical tabbing structure. The default tabbing order is in geographic
order, left-to-right, top-to-bottom. If two subforms exist side-by-side,
and each subform contains a number of field objects, the tabbing
sequence will go through the fields in the first subform before
moving on to the next.
When tabbing into a radio button, the screen reader first
reads the text for the group object that contains it, and then the
On value for the radio button. You should set custom screen reader
text for each radio button exclusion group and ensure that the On
value for radio buttons matches the caption or is some other meaningful
Images may help improve comprehension for users with some
types of disabilities, However, many screen readers do not read
graphics, which may decrease the accessibility of your form for
users with vision impairments. If you choose to use images, provide
text descriptions that describe the object and its purpose on the
The tabbing order of objects on pages and their master pages
is determined by the vertical coordinates of objects. Test your
forms to ensure that the screen reader reads objects in the order
Be aware that client-side scripts can interfere with screen
readers and keyboards if the script changes the focus of the client
application. For example, the change and mouseEnter events, when
used with drop-down lists or list boxes, have the potential to cause
inappropriate actions. Client-side scripting should be written to
avoid problems with screen readers and keyboards. Similarly, avoid
scripting events that cause visual effects, such as blinking text,
which may increase readability issues for users.
If your form has a large number of objects, tabbing in Acrobat
6.0.2 can be slow. If you are creating an Acrobat 6.0.2-compatible
form, adding unnamed subforms around smaller groups of form objects
will add levels to the logical structure and fix this problem.
authors and users should be aware of these known issues between Acrobat
and screen readers:
When users type into any field, including password fields,
screen readers read back each keystroke.
Whenever a message box opens, for example to report a validation
error, the form loses focus. Pressing Tab again moves the user back
to the first field in tabbing order.
The screen reader will read all text as if it were in the
language of the form’s Default Locale setting.
To display accessibility tags in forms with a flowable layout
in Acrobat, you must run the screen reader before opening the form
Techniques for testing form accessibility
To ensure that your forms are accessible
to a wide variety of users, you should test them with a variety
of assistive technologies. You can test your forms simply and inexpensively
using the techniques described in this section.
Ensure that the form can be filled using only the keyboard. Be
sure to fill the entire form and test all fields and buttons. As
you complete the form, determine whether improvements are required
based on your answers to the following questions:
Are there any operations that cannot be performed?
Are any operations awkward or difficult to perform?
Are keyboard mechanisms well-documented?
Do all controls and menu items have underlined access keys?
Demo versions of screen reader software can be downloaded
free from the Internet. To test screen reader results, turn your
monitor off and use only the screen reader to navigate and fill
the form. Because you are the form author, your familiarity with
the form may make it difficult to determine if the information read
by the screen reader is sufficient and makes sense. If possible, have
someone else test your form in this way.
Demo versions of screen magnification software are also available
for testing from the Internet.
Speech-to-text software is available at a nominal cost from
local computer stores. Test the form by using voice input only.
users with vision impairment rely on high contrast between text
and the background to read the form. Microsoft Windows has a high
contrast color scheme that provides a display similar to what many
users with vision impairment will be using to complete your form.
To set your display to high contrast mode, enable the feature through
Accessibility Options in the Windows Control Panel. As you complete
the form in this mode, determine whether improvements are required
based on your answers to the following questions:
Do parts of the form become invisible, unrecognizable, or
difficult to use?
Do any areas continue to appear black on a white background?
Are any elements improperly sized or truncated?