The SubForm class represents a group of fields, contained in a fixed bounding box, that you can move on the form as a unit. The bounding box constrains the locations of the fields. You cannot move the fields outside the box.

Using subforms can provide a number of programming conveniences. For example, when a subform has an associated variable, you can use that variable to reference all of the fields on the subform at once. If you map a subform to a user class, you can pass all of its data as an object between frames.

If you associate a subform with a named class definition, its component fields must map to the attributes defined for the class. If you associate the subform with a variable name but do not specify the variable's class, OpenROAD creates an unnamed class for the subform. You can use this class only within the frame that contains the subform.

You can use a subform as a convenience in editing, as a fixed set of fields that can be manipulated as one field. If so, you need not associate the subform with a variable. In such cases, OpenROAD considers the subform's component fields as part of the form as a whole (or as part of the composite field that contains the subform).