NLS_ISO_CURRENCY specifies the string to use as the international currency symbol for the C number format element.
Local currency symbols can be ambiguous. For example, a dollar sign ($) can refer to U.S. dollars or Australian dollars. ISO Specification 4217 1987-07-15 defines unique "international" currency symbols for the currencies of specific territories or countries.
The value of this initialization parameter NLS_ISO_CURRENCY is used to initialize the session value of this parameter, which is the actual value referenced by the SQL query processing. This initial value is overridden by a client-side value if the client uses the Oracle JDBC driver or if the client is OCI-based and the NLS_LANG client setting (environment variable) is defined. The initialization parameter value is, therefore, usually ignored.