This category of classes are proxy classes for the reference structure types defined in the ABAP Dictionary and can be viewed using R/3 Transaction SE11. Examples of reference structure types abound, and some well-used ones are BAPIORDERS , BAPIITEMIN , BAPIEBAN , BAPI0015_1 and BAPI0002_3 . These reference structure types contain definition of fields: field ABAP data type ( ABAP to Native Data Type Mapping), field offset, length, position and decimal places.

In the BAPI Wizard-generated parameter proxy source files, The Structure Parameter Classes and The Table Parameter Classes are based on the ABAP reference structure types. These classes provide type-safe access to individual fields of the structure or table parameters.

The following diagram shows the R/3 transaction SE11 displaying the definition of reference structure type BAPI0015_1 .