Setting Form Element as a Data Source Context
From Documentation
Setting Form Element as a Data Source Context
You may also add form elements as Combo boxes, Check boxes or Radio buttons, to which you can specify a dynamic source for populating the options of the selected form element.
Note: Form objects must be placed in a form layout region. For information on creating forms and form object definitions, see Designing and Implementing Forms.
The Checkbox and the Radio button can have dynamic functionality. The user can specify from the Data Source dialog a field used to determine if the button should be checked or not. This is done by comparing the value of the control with the value of the current line from the selected field.
