1.4 Standards Support Requirements

To conform to [ISO-8859-1], [ISO-8859-8], [ISO-8859-9], [ISO-8859-15], and [ISO-8859-16], a user agent must implement all required portions of the specification. Any optional portions that have been implemented must also be implemented as described by the specification. Normative language is usually used to define both required and optional portions. (For more information, see [RFC2119].)