Here is an example which uses check boxes (we assume you speak English!):
Unlike the radio buttons in the last example the checkboxes here have different names, though the close connection between this group of three buttons is emphasised by the sequence in them.
One property of radio buttons and check boxes is that of 'CHECKED' which is when the button has been selected. This can be set in the INPUT tag or it can be set by the user on the FORM. The eight tests performed on the three buttons consider every possible permutation of checks and output a different message for each one. The number of permutations is in the relationship 32 which is 8 - 4 boxes would give 16 permutations, and so on, which is rather a lot of coding. The action taken is to open an Alert box but any other action could be taken in its place.