extern void gstring_reset_unused(gstring *);
extern void header_add(int, const char *, ...);
+extern header_line *header_add_at_position_internal(BOOL, uschar *, BOOL, int, const char *, ...);
extern int header_checkname(header_line *, BOOL);
extern BOOL header_match(uschar *, BOOL, BOOL, string_item *, int, ...);
extern int host_address_extract_port(uschar *);