If not given, cross references render with the
.html
extension as in:<a href=not-index.html#h2-in-not-the-index>
This way, those links will work when rendering locally to
.html
files which is the default behaviour of:ourbigbook .
If given however, the links render without the which is what is needed for servers such as GitHub Pages, which automatically remove the
.html
as in:<a href=not-index#h2-in-not-the-index>
.html
extension from paths.This option is automatically implied when publishing to targets that remove the
.html
extension such as GitHub pages.