Naming the Function Module and the Function Module Group 
Purpose
Here you specify the name of the function module the BAPI is based on.
You must also specify the function group which this function module is to be assigned to. If there is not an appropriate function group, you have to specify a name for a new function group.
Process Flow
Assigning a Name to the Function Module
Choose a name for the function module which gives an indication of what the BAPI is used for.
The naming convention for BAPIs is BAPI_<Name of object type>_<method name>. You cannot exceed the maximum length of 30 characters. If need be, abbreviate the name of the method so that the assignment to the business object and to the BAPI is retained.

In the case of a GetDetail() BAPI, which reads details for the object type CompanyCode, the name of the associated function module is BAPI_COMPANYCODE_GETDETAIL.
Specifying the Function Group
All BAPIs belonging to one SAP business object type should be created in one function group, if possible. BAPIs belonging to different SAP business object types must not be created in the same function group.
Ascertain whether a function group has already been created for the BAPIs of the SAP business object type in question. If a function group does not already exist, specify a name for one to be created.
As the basis for naming the function group, you can use either the default technical name (object type) of the SAP business object type or its object name.
To find out the technical name of the business object type, open the object type in the Business Object Repository (BOR), as described in the section