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A check mark within the checkbox indicates that the setting is selected. The following figure shows both available and unavailable checkboxes in selected and unselected states.

Figure 1 CheckBoxes
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The user clicks a CheckBox to switch its setting from OFF to ON, or ON to OFF. When a CheckBox is unavailable, the user cannot change its setting.

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Figure 2 States of Checkboxes
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CheckBox Menu Items

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Figure 3 CheckBox Menu Items
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You can use checkbox menu items to present users with a nonexclusive choice.

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