The C++ classes are related to each other in two ways.
The first is the Base-Derived relationship
The F90 API supports the Base-Derived relationships through Base-Class conversion functions. These are: block, attributable, and labelled.
and the second is the Parent-Child relationship.
These relationships are handled in the F90 API through the parent() function. This function has been overloaded, and returns the parent object of the given object.
The following table shows this simple relationship:
| Handle | Class | Base Classes | Parent Class |
| ArrayT | Array | Block | - |
| Nullable | |||
| DataComponent | |||
| AttributableT | Attributable | Labelled | - |
| AttributeT | Attribute | Labelled | Attributable |
| BlockT | Block | Attributable | DataSet |
| ColumnT | Column | Attributable | Table |
| Nullable | |||
| DataComponent | |||
| DataComponentT | DataComponent | Nullable | - |
| NullableT | Nullable | - | - |
| DataSeT | DataSet | Attributable | DataSetServer |
| LabelledT | Labelled | - | - |
| TableT | Table | Block | - |
Further details are given in the section on the C++ API.
