The region is marked as polite with relevant="additions", therefore the text changes should be announced after users have completed their current activity. Since removals and additions are not specified, removals and insertions should not be announced.
After presenting the heading, the user agent should present the text in the live region area at the time. It should then proceed to the "Summary" section followed by the "Description of expected behavior" section. It should then continue to read the filler text until the end of the document and stop. Since there is no more user activity at this point, the text changes to the live region area should be announced. In addition, if the user were reading and stopping intermittently, then when the user is idling, the text changes to the live region area should be announced. However, since removals and insertions are not relevant, they should not be announced.
The filler text is here to let developers run their user agents for a longer period of time to make sure that everything will continue to behave as it should. The filler text is here to let developers run their user agents for a longer period of time to make sure that everything will continue to behave as it should. The filler text is here to let developers run their user agents for a longer period of time to make sure that everything will continue to behave as it should. The filler text is here to let developers run their user agents for a longer period of time to make sure that everything will continue to behave as it should.