mn Type
      </p>
      <p>
       Description
      </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
       <code class="structfield">map_number</code> <code class="type">int4</code>
      </p>
      <p>
       Number of this map, in priority order, if valid, otherwise
       <code class="literal">NULL</code>
      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
       <code class="structfield">file_name</code> <code class="type