-any promoted functions from those are pulled in as well. <version> can be
-given to override the version where <extension> was promoted to core."""
+any promoted functions from those are pulled in as well. <core_version> can
+be given to override the version where <extension> was promoted to core.
+
+In the second form, the parameters are read from <extfile>. If <outfile> is
+absent, the extension's lowercased name is used. Anything after the last dot
+in <outfile> is removed and replaced with cpp and h."""