, U+21D1 ISOamsa --&gt;
&lt;!ENTITY rArr     CDATA "&amp;#8658;" -- rightwards double arrow,
                                     U+21D2 ISOtech --&gt;
&lt;!-- ISO 10646 does not say this is the 'implies' character but does not have 
     another character with this function so ?
     rArr can be used for 'implies' as ISOtech suggests --&gt;
&lt;!ENTITY dArr     CDATA "&amp;#8659;" -- downwards double arrow, U+21D3 ISOamsa --&gt;
&lt;!ENTITY hArr     CDATA "&amp;#8660;" -- left right double arrow,
         