[PDF-Forms] Grouping check boxes

[Anna]

Dear all,   I've only used _javascript_ to control action within a website so using it in a pdf is confusing me a little.  I have an order form, with a tick box, which allows a user to select an item from others listed.  I have made these simple yes no boxes but I need to make them mutually exclusive.  I'm not using a combo box because of the layout of the form, and had thought of using radio buttons but it doesn't give me the freedom of using a tick symbol.   Is there a short piece of code which will allow me to take the selection and adjust it into a total box, but still allowing the user to change their mind and recalcualte using another combination.   Thank you,   Anna