Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Resource Unit
Table title:
Description
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > RU Type </th><th colspan=1 rowspan=1 > CBW20 </th><th colspan=1 rowspan=1 > CBW40 </th><th colspan=1 rowspan=1 > CBW80 </th><th colspan=1 rowspan=1 > CBW80+80 and CMW160 </th></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 26-Tone RU </td><td colspan=1 rowspan=1 > 9 </td><td colspan=1 rowspan=1 > 18 </td><td colspan=1 rowspan=1 > 37 </td><td colspan=1 rowspan=1 > 74 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 52-Tone RU </td><td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=1 > 8 </td><td colspan=1 rowspan=1 > 16 </td><td colspan=1 rowspan=1 > 32 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 106-Tone RU </td><td colspan=1 rowspan=1 > 2 </td><td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=1 > 8 </td><td colspan=1 rowspan=1 > 16 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 242-Tone RU </td><td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > 2 </td><td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=1 > 8 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 484-Tone RU </td><td colspan=1 rowspan=1 > N/A </td><td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > 2 </td><td colspan=1 rowspan=1 > 4 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 996-Tone RU </td><td colspan=1 rowspan=1 > N/A </td><td colspan=1 rowspan=1 > N/A </td><td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > 2 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 2x996 Tone RU </td><td colspan=1 rowspan=1 > N/A </td><td colspan=1 rowspan=1 > N/A </td><td colspan=1 rowspan=1 > N/A </td><td colspan=1 rowspan=1 > 1 </td></tr>
</table>
Question:
What types of resource units are there?
Answer:
The RUs defined are 26-tone RU, 52-tone RU, 106-tone RU, 242-tone RU, 484-tone RU, 996-tone RU and 2x996-tone RU.