<!DOCTYPE mathtest SYSTEM "mathtest.dtd" [
<!ENTITY charge-density "<var>&rho;</var>">
<!ENTITY current-density "<vec>j</vec>">
<!ENTITY electric-field "<vec>E</vec>">
<!ENTITY light-speed "<var>c</var>">
<!ENTITY magnetic-field "<vec>B</vec>">
<!ENTITY permittivity-vacuum
	"<index><var>&epsilon;</var><const>0</const></index>">
<!ENTITY time "<var>t</var>">
]>
<mathtest>
  <eqns>
    <eqn>
      <dot>
	<vec>&nabla;</vec>
	<vec>E</vec>
      </dot>
      <divide>
	<var>&rho;</var>
	<index>
	  <var>&epsilon;</var>
	  <const>0</const>
	</index>
      </divide>
    </eqn>
    <eqn>
      <cross>
	<vec>&nabla;</vec>
	<vec>E</vec>
      </cross>
      <neg>
	<diff>
	  <vec>B</vec>
	  <var>t</var>
	</diff>
      </neg>
    </eqn>
    <eqn>
      <mult>
	<exp>
	  <var>c</var>
	  <const>2</const>
	</exp>
	<cross>
	  <vec>&nabla;</vec>
	  <vec>B</vec>
	</cross>
      </mult>
      <add>
	<diff>
	  <vec>E</vec>
	  <var>t</var>
	</diff>
	<divide>
	  <vec>j</vec>
	  <index>
	    <var>&epsilon;</var>
	    <const>0</const>
	  </index>
	</divide>
      </add>
    </eqn>
    <eqn>
      <dot>
	<vec>&nabla;</vec>
	<vec>B</vec>
      </dot>
      <const>0</const>
    </eqn>
  </eqns>
  <eqns>
    <eqn>
      <div>
	<vec>E</vec>
      </div>
      <divide>
	<var>&rho;</var>
	<index>
	  <var>&epsilon;</var>
	  <const>0</const>
	</index>
      </divide>
    </eqn>
    <eqn>
      <curl>
	<vec>E</vec>
      </curl>
      <neg>
	<diff>
	  <vec>B</vec>
	  <var>t</var>
	</diff>
      </neg>
    </eqn>
    <eqn>
      <mult>
	<exp>
	  <var>c</var>
	  <const>2</const>
	</exp>
	<curl>
	  <vec>B</vec>
	</curl>
      </mult>
      <add>
	<diff>
	  <vec>E</vec>
	  <var>t</var>
	</diff>
	<divide>
	  <vec>j</vec>
	  <index>
	    <var>&epsilon;</var>
	    <const>0</const>
	  </index>
	</divide>
      </add>
    </eqn>
    <eqn>
      <div>
	<vec>B</vec>
      </div>
      <const>0</const>
    </eqn>
  </eqns>
  <eqns>
    <eqn>
      <div>
	&electric-field;
      </div>
      <divide>
	&charge-density;
	&permittivity-vacuum;
      </divide>
    </eqn>
    <eqn>
      <curl>
	&electric-field;
      </curl>
      <neg>
	<diff>
	  &magnetic-field;
	  &time;
	</diff>
      </neg>
    </eqn>
    <eqn>
      <mult>
	<exp>
	  &light-speed;
	  <const>2</const>
	</exp>
	<curl>
	  &magnetic-field;
	</curl>
      </mult>
      <add>
	<diff>
	  &electric-field;
	  &time;
	</diff>
	<divide>
	  &current-density;
	  &permittivity-vacuum;
	</divide>
      </add>
    </eqn>
    <eqn>
      <div>
	&magnetic-field;
      </div>
      <const>0</const>
    </eqn>
  </eqns>
</mathtest>
