her numbers, so as an optimization you can decide to use those tags for the commonly used or repeated elements, leaving tags 16 and higher for less-commonly used optional elements. Each element in a repeated field requires re-encoding the tag number, so repeated fields are particularly good candidates for this optimization.</p>
<p>Each field must be annotated with one of the following modifiers:</p>
<ul>
  <li><code>required</code>: a value for the field must be provided, otherwise the message will be consi