What is <ol type=a> used for code example

Example: ol types

<ol type="1">
  <li>The list items will be bulleted with numbers (default)</li>
</ol>
<ol type="A">
  <li>The list items will be bulleted with Capital(UPPERCASE) letters</li>
</ol>
<ol type="a">
  <li>The list items will be bulleted with with small(lowercase) letters</li>
</ol>
<ol type="I">
  <li>The list items will be bulleted with with Capital(UPPERCASE) Roman letters</li>
</ol>
<ol type="i">
  <li>The list items will be bulleted with with small(lowercase) Roman letters</li>
</ol>