Either a Combo Box or a List box would work. A combobox implies a choice of only one can be made. A Listbox implies that one or more can be chosen and it only takes a single click to change between choices.

I would make the template type a combo box. And the available variables a list box. If you set the listbox to have multiple columns then it can also store the values assigned to each variable. Then code it so that you can click on a variable and type into a nearby Textbox to create/edit the value assigned to that variable.

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Andrew Lockton
Chrysalis Design, Melbourne Australia