If you wish to communicate via IDocs with earlier R/3 Systems (Rel. 2.1 to 3.1) or with external systems (for example EDI subsystems) based on the same releases, you must inform your system via the version in the port definition. This ensures that the correct IDocs record types are sent during outbound processing.

Two problems can arise not only in the case of older R/3 releases, but also in the case of R/2 Systems:

• You are using long names for message types, IDoc types or segments. Older releases only support names with up to:

• You are using extensions which have been defined for Release 4.X. Older releases (3.0, 3.1) either use other fields to identify these extended IDoc types internally or do not support extensions at all (Rel. 2.1 & 2.2 and R/2 Systems).

In both cases, you must maintain the conversion tables in Customizing. These tables convert the old names into new names. The two cases described above can occur at the same time.

During outbound processing, the system determines the correct IDoc record types via the port version.

The old names (in the case of outbound processing) or the new names (in the case of inbound processing) are determined from the conversion tables and if new extensions are being used, the required fields in the control record are maintained (outbound processing).

The port version is used to determine the release status of the system with which you are communicating. The following versions are used:

• Version 1: Releases 2.1/2.2
• Version 2: Releases 3.0/3.1 and R/2 Systems. As each R/2 System is connected to the R/3 System via the port type "CPI-C" and each CPI-C port is connected to an R/2 System, version 2 is already defined for this port type and cannot be changed in the port definition.
• Version 3: Release 4.X (default value)

Maintain the corresponding conversion tables in Customizing, according to the problems described above.