Substructures 

In addition to listing the individual fields, you can also include the fields of another table or structure as a substructure in tables and structures. If the substructure is changed, the tables or structures including this structure are automatically adjusted. Individual fields and substructures can be merged as required.

Substructures can also be nested, that is a structure includes a structure which in turn includes another structure, etc. The maximum nesting depth is limited to nine. The maximum length of a path of nested substructures in a table or structure is therefore nine (the table/structure itself not included).

Only flat structures can be included as substructures. In a flat structure, every field either refers to a data element or is assigned a data type and length by direct type entry.

At most one table may reside on a path of nested substructures.

Table TAB1 includes a structure STRUCT1 which in turn includes structure STRUCT2. Only table TAB1 resides on the path of the nested substructures. It is also possible to include TAB1 in a further structure STRUCT0.

On the other hand, no other table may be included in TAB1 since in this case two tables (TAB1 and TAB2) would reside on a path of nested substructures.

See also:

Including Substructures