What is the correct syntax that needs to be used in Checkboxes, Radiogroups and Selectboxes 

When creating a checkbox group, a radio group or a selectbox, you need to use a specific syntax inside the default value textbox.

Let's assume that you have a checkbox group and want to display 3 cities, Paris, London, Milan. Your syntax should be:

Paris|Paris,London|London,Milan|Milan

Why the duplicated words? That's because you can set the field to show something to the user, and return something else to you. For instance, if you want your checkbox group to return the country, but show the user the cities, you should use:

France|Paris,UK|London,Italy|Milan

This way, the user will see Paris, London and Milan, but you'll get France, UK, Italy in the backend, in the thank you message and in the emails.

You can also use the {checked} syntax to make some options selected by default:

Paris{checked}|Paris,London|London,Milan{checked}|Milan

This example will select by default Paris and Milan when the form is initially shown to the user.