Alter Aeon Online Help

Keywords are:  'sitting prone debuff'

If you are 'sitting', you are on your bottom, feet off the ground, but with your
arms free and functional. Your cannot use certain attacks and your armor is
decreased, but you can still fight.

If you are knocked 'prone', you are laying on your back, feet off the ground,
unable to effectively make attacks and lowering your armor and defenses. You
will automatically attempt to stand after a short time.

Generally, only stunned creatures can be knocked prone. You can knock
opponents prone using attacks that would normally push them into a sitting
position, such as 'trip', 'bash' or spells such as 'gust'.