ng="2" cellpadding="0">
    <tr><td valign="top"></td><td valign="top"><em>c</em>&nbsp;</td><td>hash_class index </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>p</em>&nbsp;</td><td>perimeter level index </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>l</em>&nbsp;</td><td>longest edge length index </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>s</em>&nbsp;</td><td>shortest edge length index </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>bucket_begin<