+void whlp_backend(paragraph *, keywordlist *, indexdata *, void *);
+paragraph *whlp_config_filename(char *filename);
+
+/*
+ * bk_man.c
+ */
+void man_backend(paragraph *, keywordlist *, indexdata *, void *);
+paragraph *man_config_filename(char *filename);
+
+/*
+ * bk_info.c
+ */
+void info_backend(paragraph *, keywordlist *, indexdata *, void *);
+paragraph *info_config_filename(char *filename);
+
+/*
+ * bk_paper.c
+ */
+void *paper_pre_backend(paragraph *, keywordlist *, indexdata *);
+
+/*
+ * bk_ps.c
+ */
+void ps_backend(paragraph *, keywordlist *, indexdata *, void *);
+paragraph *ps_config_filename(char *filename);
+
+/*
+ * bk_pdf.c
+ */
+void pdf_backend(paragraph *, keywordlist *, indexdata *, void *);
+paragraph *pdf_config_filename(char *filename);