A Checkbox can be used to represent the value of a group of checkboxes, presenting as:
checked, when the entire group is checked,
unchecked, when the entire group is unchecked, or
mixed, when the group has some of each.
For mixed state checkboxes, you can set the checked prop to "mixed", or provide an array of checked values (e.g. [true, false, false]) to calculate the tri-state value.