
In order to fetch Code List from the fixed values of a Domain, a GSDO Type should be created for Code List.
To create a GSDO Type proceed as follows:
In transaction SPRO open the SAP Reference IMG and navigate to: and click on the Activity icon.
Create a GSDO Type by choosing the New Entries button.
Follow the example given below to create a new GSDO Type:
GSDO Type: DOCUMENTTYPE
CompName: IWCLST (GenIL model Name)
GSDO Data Object Name: CODELIST (Root Object of GeniL)
Save the created GSDO Type
Select the GSDO type created above and choose GSI implementation from the Dialog Structure in the left pane.
The Generic Groupware Service Interface (GSI) defines the contract between the Generic Service Provider and all GSI implementations. Consequently all GSI implementation must implement this interface. For more information, see IMG activity documentation for GSDO Types & GSDO Contexts & GSI Implementations.
Configure anyone of the following Adaptation BSO's as the Class/Interface in the GSI Implementation:
Adaptation BSO to fetch code list from a domain : /IWCNT/CL_CLST_ABSO_DOMAIN
Adaptation BSO to fetch code list from the QueryCodeList ESA service: /IWCNT/CL_CLST_ABSO_ESA
Adaptation BSO to fetch code list from a BAPI : /IWCNT/CL_CLST_ABSO_BAPI
For every GSDO Type, the concept of multi destination BSO can be implemented using GSI Implementation i.e. data can come from different software versions. Mapping to each designated system is identified here.
In case of Multi Destination BSO, at least two system aliases need to be maintained in the GSDO group associated with the GSDO type.
As shown in the image below the Multi destination BSO implements Interface: /IWCNT/CL_BSO_MD_CLST_DFL, and the GSI entry corresponds to MSDO (Multi Destination BSO) which incorporates two other (at least) Adaptation BSO’s ABSO_DOMAIN and ABSO_ESA. Also, for different Software Versions different Interface Implementation can be mapped.
For the given software version, if the code list needs to be fetched from the QueryCodeList ESA service, then the Adaptation BSO configured should be /IWCNT/CL_CLST_ABSO_ESA. In addition to this, the ESA relevant parameters need to be maintained in the customizing view. For more information, see the IMG documentation for Maintain Code Type.
For the given software version, if the code list needs to be fetched from a domain, then the Adaptation BSO configured should be /IWCNT/CL_CLST_ABSO_DOMAIN. In addition to this the domain name need to be maintained in the customizing view. For more information, see the IMG documentation for Maintain Code Type.
For the given software version, if the code list needs to be fetched for a BAPI parameter then Adaptation BSO configured should be /IWCNT/CL_CLST_ABSO_BAPI. In addition to this, the BAPI relevant parameters need to be maintained in the customizing view. For more information, see the IMG documentation for Maintain Code Type.

Default Software Version is generally implemented when no other system is designated to fetch the code list.