A field group is the hidden parent of field-level widgets and child frames owned by a parent frame or dialog box. Thus, field groups are the actual children of frames and dialog boxes. A frame contains the following field groups:
A background field group (which includes the frame header)
For a one-down frame or dialog box: a single data field group containing field-level widgets and child frames
For a multiple-down frame: one data field group for each data iteration in the frame
A field group has no visible representation. You cannot explicitly define or create field groups. They are generated automatically when frames are defined or created.
A background field group (which includes the frame header)