AUTHENTICATION_DATA
　　Data being used to authenticate the login user. For X.503 certificate authenticated sessions, this field returns the context of the certificate in HEX2 format.
　　Note: You can change the return value of the AUTHENTICATION_DATA attribute using the length parameter of the syntax. Values of up to 4000 are accepted. This is the only attribute of USERENV for which Oracle implements such a change.

　　AUTHENTICATION_TYPE
　　How the user was authenticated:
　　DATABASE: username/password authentication
　　OS: operating system external user authentication
　　NETWORK: network protocol or ANO authentication
　　PROXY: OCI proxy connection authentication
　　BG_JOB_ID
　　Job ID of the current session if it was established by an Oracle background process. Null if the session was not established by a background process.
　　CLIENT_INFO
　　Returns up to 64 bytes of user session information that can be stored by an application using the DBMS_APPLICATION_INFO package.

　　CURRENT_SCHEMA
　　Name of the default schema being used in the current schema. This value can be changed during the session with an ALTER SESSION SET CURRENT_SCHEMA statement.

　　CURRENT_SCHEMAID
　　Identifier of the default schema being used in the current session.

　　CURRENT_USER
　　The name of the user whose privilege the current session is under.

　　CURRENT_USERID
　　User ID of the user whose privilege the current session is under.

　　DB_DOMAIN
　　Domain of the database as specified in the DB_DOMAIN initialization parameter.

　　DB_NAME
　　Name of the database as specified in the DB_NAME initialization parameter.

　　ENTRYID
　　The available auditing entry identifier. You cannot use this option in distributed SQL statements. To use this keyword in USERENV, the initialization parameter AUDIT_TRAIL must be set to true.

　　EXTERNAL_NAME
　　External name of the database user. For SSL authenticated sessions using v.503 certificates, this field returns the distinguished name (DN) stored in the user certificate.

　　FG_JOB_ID
　　Job ID of the current session if it was established by a client foreground process. Null if the session was not established by a foreground process.

　　HOST
　　Name of the host machine from which the client has connected.