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:
Kilowatt hour
Table title:
Watt hour multiples and billing units
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=3 rowspan=1 > Submultiples </th><td colspan=1 rowspan=12 >  </td><th colspan=3 rowspan=1 > Multiples </th></tr>
<tr> <th colspan=1 rowspan=1 > Value </th><th colspan=1 rowspan=1 > Symbol </th><th colspan=1 rowspan=1 > Name </th><th colspan=1 rowspan=1 > Value </th><th colspan=1 rowspan=1 > Symbol </th><th colspan=1 rowspan=1 > Name </th></tr>
<tr> <td colspan=1 rowspan=1 > 10−3 </td><td class="highlighted"  colspan=1 rowspan=1 > mW⋅h </td><td class="highlighted"  colspan=1 rowspan=1 > milliwatt hour </td><td colspan=1 rowspan=1 > 103 </td><td class="highlighted"  colspan=1 rowspan=1 > kW⋅h </td><td class="highlighted"  colspan=1 rowspan=1 > kilowatt hour </td></tr>
<tr> <td colspan=1 rowspan=1 > 10−6 </td><td colspan=1 rowspan=1 > µW⋅h </td><td colspan=1 rowspan=1 > microwatt hour </td><td colspan=1 rowspan=1 > 106 </td><td class="highlighted"  colspan=1 rowspan=1 > MW⋅h </td><td class="highlighted"  colspan=1 rowspan=1 > megawatt hour </td></tr>
<tr> <td colspan=1 rowspan=1 > 109 </td><td colspan=1 rowspan=1 > GW⋅h </td><td colspan=1 rowspan=1 > gigawatt hour </td></tr>
<tr> <td colspan=1 rowspan=1 > 1012 </td><td colspan=1 rowspan=1 > TW⋅h </td><td colspan=1 rowspan=1 > terawatt hour </td></tr>
<tr> <td colspan=1 rowspan=1 > 1015 </td><td colspan=1 rowspan=1 > PW⋅h </td><td colspan=1 rowspan=1 > petawatt hour </td></tr>
</table>
Question:
What is the symbol of kilowatt hour, megawatt hour and milliwatt hour?
Answer:
The symbol of kilowatt hour is kW⋅h, megawatt hour is MW⋅h and milliwatt hour is mW⋅h.