Reading order is the sequence in which a screen
reader reads all static objects (such as text and images) and field
objects in a form. In PDF files, reading order is provided to the
screen reader as a tree structure. Reading order always moves in a
linear fashion and presents each piece of information on the form
once. It also enables the user to read in the same order whether
they are reading forward or backward.
Tabbing order determines how a user navigates through fields
in a form using the keyboard. By default, Designer automatically
sets the tabbing order for each form using geographical order (left-to-right,
top-to-bottom). You can customize it using the Tab Order palette.
The tabbing order is not necessarily linear.
Reading order restrictions
Designer uses the default or custom
tabbing order to determine the reading order tree structure. However,
because the reading order has different restrictions (for example,
a linear structure) Designer generates the reading order and tabbing
order separately. If you want both types of ordering to use the
same sequence, ensure that the tabbing order conforms to the restrictions
for the reading order.
Reading order and subforms
Subforms organize content on a form
and improve performance when the user tabs between fields. The reading
order treats subform objects as a group. All objects in a subform
must be read before any objects in a subsequent subform are read.
Although
you can customize the tabbing order to navigate between objects
in different subforms, this type of navigation is not possible in
the reading order. To maintain consistency between the reading and
tabbing order, always tab through all the objects in a subform before
navigating to another subform.
Static text objects and tabbing order
Static text objects are
included in the tabbing order to enable you to modify their placement
in the reading order. Headers and section titles are examples of
static text objects. However, text objects are excluded from keyboard
navigation. Changing the place of text objects in the tabbing order
does not affect a user who is navigating using the keyboard.
