Both the Columns and its inner Column block will often be used for structural sections on the page. Users/Themers should be able to set the HTML element used.

Currently, both blocks are wrapped in a <div>. However, <main>, <section>, <aside>, and <article> will make sense in various use cases.

<header> and <footer> could potentially make sense for the outer Columns block, but I'd like to focus on getting the other options in for sure.