/**
* Generate a diff, no caching.
*
- * Subclasses may override this to provide a
+ * This implementation uses generateTextDiffBody() to generate a diff based on the default
+ * serialization of the given Content objects. This will fail if $old or $new are not
+ * instances of TextContent.
+ *
+ * Subclasses may override this to provide a different rendering for the diff,
+ * perhaps taking advantage of the content's native form. This is required for all content
+ * models that are not text based.
*
* @param $old Content: old content
* @param $new Content: new content
*
* @since 1.21
+ * @throws MWException if $old or $new are not instances of TextContent.
*/
function generateContentDiffBody( Content $old, Content $new ) {
if ( !( $old instanceof TextContent ) ) {