This script's functionality is known my many names: Dependent Dropdowns / Cascaded Selects / Multiple Comboboxes and other permutations.

MultiSelect is a Dependent Dropdown script using client-side array-based data. The script was created to address the shortcomings of similar free scripts; It is recommended when the advanced features of SelectCascade are not required.

• Does not need a server-side database
• Multiple Independent groups
• Unlimited number of listboxes per group
• Hides un-populated lists (Optional)
• Unobtrusive Installation
• Can run a user callback function

If you find the data array system daunting, we would suggest an upgrade to SelectCascade, which by virtue of its code generator is easier to configure and maintain.