An IDoc message is organized hierarchically with one top-level parent segment and one or more second-level child segments. Second-level child segments can also have one or more third-level child segments.

To maintain the structure of the IDoc data, the IDoc Prepare transformation uses primary and foreign keys. The top-level parent segment has a primary key. Each child segment has a primary key and a foreign key. The foreign key of each child segment references the primary key of its parent segment. For example, the foreign key of a second-level child segment references the primary key of the top-level parent segment. Similarly, the foreign key of a third-level child segment references the primary key of the second-level child segment.

The IDoc Prepare transformation groups incoming IDoc data based on the values in the primary and foreign key fields. The Control Input group of the IDoc Prepare transformation represents the parent segment. All other groups of the IDoc Prepare transformation except the ErrorIDocData group represent second-level or third-level child segments.

The following table shows the groups of the IDoc Prepare transformation and the fields used for the primary and foreign keys:

Each value for the GPK_<name> field needs to be unique. Each GFK_<parent_name>_<group_name> field needs to reference the primary key of its parent segment.

For example, the following table shows the relationship of primary and foreign keys in an IDoc message named ABSEN1 with four child segments:

The IDoc Prepare transformation uses these primary and foreign key relationships to maintain the structure of the IDoc data. Any foreign key field that does not match the primary key of its parent segment results in an orphan row. Any primary key field that is not unique results in a duplicate row.

Verify that each IDoc message has a unique primary key for the top-level parent segment, each child segment, and that each foreign key matches the primary key of its parent.