SQL> select distinct ISSYS_MODIFIABLE from v$system_parameter;
ISSYS_MOD
---------
IMMEDIATE
FALSE
DEFERRED
SQL>
SQL> select * from v$version;
BANNER
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Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi
PL/SQL Release 10.2.0.5.0 - Production
CORE 10.2.0.5.0 Production
TNS for Linux: Version 10.2.0.5.0 - Production
NLSRTL Version 10.2.0.5.0 - Production
ISSYS_MODIFIABLE VARCHAR2(9) Indicates whether the parameter can be changed with ALTER SYSTEM and when the change takes effect:
IMMEDIATE - Parameter can be changed with ALTER SYSTEM regardless of the type of parameter file used to start the instance. The change takes effect immediately.
DEFERRED - Parameter can be changed with ALTER SYSTEM regardless of the type of parameter file used to start the instance. The change takes effect in subsequent sessions.
FALSE - Parameter cannot be changed with ALTER SYSTEM unless a server parameter file was used to start the instance. The change takes effect in subsequent instances.