With a check box, you make a decision between two opposite choices or between 2 opposite choices and null. The check box label indicates the selected state, the meaning of the cleared state is the opposite of the selected state.

Figure 1: Example of a check box

With a selected and  unselected state check boxes usually represent Boolean data. However in some cases that data might also allow null values (3 valued logic). This null state is displayed as fully filled check box. If the check box allows null values you can set the value to null clicking twice on the check box or by hitting Space twice.

In this documentation we refer to check boxes as check box together with the label text, or simply by the label text.

Table 1: Keyboard shortcuts for check boxes