Release 10.1A: OpenEdge Development:
Progress 4GL Handbook

Frame parenting

You can place a dynamic field-level object in either a static or a dynamic frame. To do this, assign the frame handle to the FRAME attribute of the object. For a field-level object, there is also a PARENT attribute. Remember that there is a field group object that acts as the immediate container for field-level objects, in effect in between the frame and the individual objects. The PARENT attribute points to the field group, not the frame. Progress automatically puts the object into a field group when you assign its FRAME attribute and also when you assign the object a default tab position, if it can receive input.