The concrete types described in
\xref[\instead{sections}]{sec:structures.common} and
-\ref{sec:structures.root} are declared by the header file @|<sod/sod.h>|.
+\ref{sec:structures.root} are declared by the header file
+@|<sod/sod.h>|.\footnote{%
+ This isn't completely true. The @|SodObject| and @|SodClass| structures
+ are defined in a header called @|<sod/sod-base.h>|, which is generated by
+ the Sod translator; but @|<sod/sod.h>| includes @|<sod/sod-base.h>|, so you
+ can forget about this detail.} %
The definitions described in \xref{sec:structures.layout} are defined in the
header file generated by the containing module.