Are html tables valid if there are multiple tbody tag used?

Question

If there are multiple <tbody> tags in an HTML <table>, is this valid?

<table>
    <tbody>
    </tbody
    <tbody>
    </tbody
</table>

Answer 1

Yes, the DTD shows that it is allowed.

<!ELEMENT table
     (caption?, (col*|colgroup*), thead?, tfoot?, (tbody+|tr+))>

The DTD also has a comment which explains why:

Use multiple tbody sections when rules are needed between groups of table rows.

Answer 2

I copy pasted your title in google and the first link is : http://www.w3.org/TR/html401/struct/tables.html#h-11.2.3 ,

"Table rows may be grouped into a table head, table foot, and one or more table body sections",

so yes you can !

Answer 3

Multiple table bodies is perfectly acceptable.

Answer 4

Yes, you can have multiple tbodys in the same table.

Example:

<table>
    <tbody>
        <tr><td>Monday</td><td>#1</td></tr>
        <tr><td>Friday</td><td>#2</td></tr>
    </tbody>
    <tbody>
        <tr><td>Monday</td><td>#3</td></tr>
        <tr><td>Friday</td><td>#4</td></tr>
    </tbody>
</table>