Form fillers tab to move through a form guide. Form fillers also use the arrow keys to move between items in a list and the Tab key to move out of the list. The same is true for a group of radio buttons. Pressing the spacebar selects objects such as a radio button, a check box, or a navigation button.
The tabbing order depends on whether a screen reader is used to access the form guide. It is good practice to test the form guide as you work to ensure that accessibility works as expected.
When a screen reader is not used, the tabbing order starts at the top of the data entry panel, moving left to right until reaching the bottom. Tabbing order then moves left to right between the navigation buttons and then left to right in the PDF toolbar. The navigational panel and guide help panel are ignored.
Tabbing order starts at the top of the data entry panel, moving left to right until reaching the bottom. Tabbing order then moves left to right between the navigation buttons and then left to right in the PDF toolbar. The navigational panel and guide help panel are ignored. A help icon is included with the PDF icons if Guide help is present. The help icon is included in the tabbing order.
Tabbing order starts at the start of the text in the guide help panel. If the help content includes a video, the next tab stops on the video button. The form filler presses the spacebar to start the video, and then again to stop the video and return to the guide help panel.
If both panel help and guide help are available in the help center, panel help is displayed by default and guide help is available at the bottom of the help center. The next tab stops on the guide help bar at the bottom of the help center. The form filler presses the spacebar to move the focus to the help contents.
From the help panel, the next tab stops at the top of the data entry panel, moving left to right until reaching the bottom. Tabbing order then moves left to right between the navigation buttons and then left to right in the PDF toolbar. The navigational panel is ignored.
See also 

Navigating accessible form guides