Math.ent

<!ENTITY phi “&#x3C6;”>

<!ENTITY alpha  “&#x3B1;”>

 

MyDocument.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE root[

    <!ENTITY % math SYSTEM “math.ent”>

    %math;

]>

<root>

    <line>&phi; value is 22.7</line>

    <line>Let &alpha; be value of circumference of circle</line>

</root>