what are type fields
<p><em>I have learned that</em><br>
 <code>type fields is an error-prone technique somewhere</code> </p>

<p>I have <strong>Google</strong> it much but no satisfactory results .Although I know the meaning of <code>type</code> and <code>fields</code> individually . I am thinking that type field means field of a particular type like </p>

<pre><code>class marks;
class test {
marks number;
bool pass;
}
</code></pre>

<p>Here according to me type field is number and pass .
If this is right how is composition different from it?
Also what is <code>type field</code> technique?? How it is error prone??  </p>

<p>Please give it true meaning. Also give an example to show its evil nature and what are its substitutes ??</p>
