Missing SID_LIST_ value left of equation for SID description in LISTENER.ORA

# listener.ora Network Configuration File: /opt/11g/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =(SID_LIST =(SID_DESC =(SID_NAME = PLSExtProc)(ORACLE_HOME = /opt/11g/oracle/product/11.2.0/dbhome_1)(PROGRAM = extproc))(SID_DESC=
(GLOBAL_DBNAME = orcl)
(ORACLE_HOME = /opt/11g/oracle/product/11.2.0/dbhome_1)
(SID_NAME = orcl)
))
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.146.131)(PORT = 1521))
    )
  )ADR_BASE_LISTENER = /opt/11g/oracle