Form variable notes and considerations

When using form variables in an action page, keep the following guidelines in mind:

A form variable is available on the action page and pages that it includes.
Prefix form variables with "Form." when referencing them on the action page.
Surround variable values with number signs (#) for output.
Variables for check boxes, radio buttons, and list boxes with size attributes greater than 1 only get passed to the action page if you select an option. Text boxes, passwords, and textarea fields pass an empty string if you do not enter text.
An error occurs if the action page tries to use a variable that was not passed.
If multiple controls have the same name, one form variable is passed to the action page with a comma-delimited list of values.
You can validate form variable values on the client or the server.