RADIO data elements allow for a one-to-many relationship between identifier and value. In other words, they have multiple possible values, but only one can be predisplayed or selected. They are best for small sets of options, generally between two and ten, which need more than a word or two of text to identify themselves.

Unfortunately, it’s somewhat more difficult to represent stored data in a radio button than in a check box or text field. This is because there is only one possible value for a text or textarea and only two possible values for a check box—but radio buttons can have more than two possible values. Therefore, you will have to output part of the actual form with PHP. This looks a little bit less neat than the styles we employed previously, so you have to go to a little more trouble to have an easily readable script. Again, the user-interface experience allowed by radio buttons is worth the extra trouble it gives to the Web developer.