The html5 plugin use the 960 Grid System, which allows technical writters to use the attribute outputclass to positions their elements on the grid.

The following code

   <p outputclass="grid_2">...</p>
<p outputclass="grid_2">...</p>
<p outputclass="clear-before">Always clear after</p>

will output content:

This paragraph should have 3 columns width and should be parrallel to the next paragraph.

This paragraph (5 columns) is on the right side of the previous one. The difference with the css columns layout feature is that theses 2 paragrahs does not flow automatically one in the other,

Please see the 960 Grid System documentation to see the availaible class.