Author: Christoph Dorn Format: MarkdownItexexpanded the page a bit
<a href="https://ncatlab.org/nlab/revision/diff/surface+diagram/2">diff</a>, <a href="https://ncatlab.org/nlab/revision/surface+diagram/2">v2</a>, <a href="https://ncatlab.org/nlab/show/surface+diagram">current</a>