Passing A Conditional Form Variable (Was: 'Trying To Use Images Asform Submit Buttons')

What I need to do is to pass a conditional variable to the target URL,
when the form is submitted, depending on which graphic button is pressed.

So, the form already sends several variables when the form is submitted
(at the onclick event). I've confirmed this by capturing the HTTP POST
variables and displaying them when the page executes.

Now, depending on which graphic button is selected, I would like to pass
another variable.

For example, when the Create button is pressed, I would like to pass
create=true (or something signifying that 'create' is set) to the target
URL......