-henceforth known as the IBG. The new edition will be in a new source
-format that's more contributor-friendly (see below). It's a
-work-in-progress; see the [issue tracker](https://github.com/i6/ibg/issues)
-for how it's going.
-
-The rationale for this 4th edition is:
+henceforth known as the IBG. This version is in a new source format that's
+more version-control and contributor-friendly:
+[Sphinx](http://sphinx-doc.org), a documentation build tool written in
+[Python](http://python.org). With Sphinx, the source files are in a very
+readable format called
+[reStructuredText](https://en.wikipedia.org/wiki/ReStructuredText).
+
+This version of the IBG is a work-in-progress; see the
+[issue tracker](https://github.com/i6/ibg/issues) for how it's going.
+Initially it will be a straight conversion of the 3rd edition. After that,
+the 4th edition will be prepared. The rationale for a 4th edition is: