Oracle Network Administration - Oracle 10g Database Administration Concepts and Implementation Made Simple - page 218

Figure 8-20: Service Name is the Global Database Name of the Oracle
Database your connection will be bequeathed to.
Service Name over here is the parameter where you specify the
global database name of Oracle database you what the listener to
bequeath the connection in our case it is takveen. Click the
“Next” button. The next popped up window will give you the
opportunity to test the connection and see that your configured
Net Service Name “fan” is resolving properly using tnsname.ora.