Each OID arc is associated with a mandatory number (used fordata transfer)
and an optional, recommended, identifier (for legibility). <!--This is called
the NameAndNumberForm in <ahref="http://itu.int/ITU-T/X.680">Rec. ITU-T X.680 | ISO/IEC 8824-1</a>, clause 32.--><br>An identifier begins with a lower-case letter and is followed by letters,
digits and hyphens. In the cases listed in the following table, the
identifier has been standardized <!--in <ahref="http://itu.int/ITU-T/X.660">Rec.ITU-T X.660 | ISO/IEC 9834-3</a>--> and can be used alone (without its
associated number) in the ASN.1 notation<!--; this is called the NameForm
in <ahref="http://itu.int/ITU-T/X.680">Rec. ITU-T X.680 | ISO/IEC 8824-1</a>, clause 32.-->
of an OID. Standardized identifiers are defined in <ahref="http://itu.int/ITU-T/X.660">Rec. ITU-T X.660</a> | ISO/IEC 9834-1, clauses A.2.3, A.3.2, A.3.3.1 and A.4.2.</p>