See the "Component" field in the Modify the access (of a logical entity) dialog box.
Example:
The following objects:
ID_ENTRY_FIELD (Entry field BGO),
ID_COMBO_BOX (Combo box BGO),
ID_COL_LIST (List BGO),
ID_LIST_EMPTY (List BGO),
ID_COLUMN (Column BGO)
are placed in the layout.
The ID_COL_LIST object contains the ID_COLUMN object.
The list of components only contains the layout name and the ID_COL_LIST object, because:
the objects ID_ENTRY_FIELD and ID_COLUMN do not have any LIST type properties;
the ID_LIST_EMPTY object does not contain any columns, meaning that its LIST property does not contain any properties, and as such, no VALUE properties;
the ID_COMBO_BOX object has a LIST type property, but this property is formed exclusively from the CURRENT_VALUE property of the same object (ID_COMBO_BOX) (by building this object class), and therefore does not have a VALUE property component;
the ID_COL_LIST object has a LIST type property composed with the VALUE property of the ID_COLUMN object (by building the List and Column object classes).