Hi Sandeep,
Actually the ESSTD constant maintained in the table t511k denotes whether you want the actual column or through proposed column to be entered by the end users while raising the request in ESS.
if IFD_APLVL = 1.
efd_apgrp = 'DEFAULT_GROUP' default approver is correct
In the above code you are just returning the approver group value also return the personnel number (EFD_APERN ) of the approver.
And in the table V_T77WWW_CLAGAPA make user you assign the username of the approver to the approver group.
Regards,
Mithun K