The Twoparam is edited using the fields:
Prompt [X] On(or Off) Prompt1 Val1 Prompt2 Val2
Selecting the checkbox changes the state of the BOOL, changes the label after the checkbox, and grays or ungrays the rest of the object's additional prompts and values. When the checkbox shows a check mark, the BOOL is TRUE, the label is "On" and the text is black. When the checkbox is not checked, the BOOL is False, the label is Off, and the text is grayed out and cannot be edited.
When the operator enters a value into Val1 or Val2, Setup attempts to turn it into a valid REAL and replace the REAL in Twoparam with it. For example, if an operator puts in "1", Setup() changes it to "1.0". If Setup() cannot translate a string into a REAL, it defaults to the value 0.0.