-extern ax25_address null_ax25_address;
-extern char *ax2asc(ax25_address *);
-extern ax25_address *asc2ax(char *);
-extern int ax25cmp(ax25_address *, ax25_address *);
-extern int ax25digicmp(ax25_digi *, ax25_digi *);
-extern unsigned char *ax25_addr_parse(unsigned char *, int, ax25_address *, ax25_address *, ax25_digi *, int *, int *);
-extern int ax25_addr_build(unsigned char *, ax25_address *, ax25_address *, ax25_digi *, int, int);
-extern int ax25_addr_size(ax25_digi *);
-extern void ax25_digi_invert(ax25_digi *, ax25_digi *);
+extern const ax25_address ax25_bcast;
+extern const ax25_address ax25_defaddr;
+extern const ax25_address null_ax25_address;
+extern char *ax2asc(char *buf, const ax25_address *);
+extern void asc2ax(ax25_address *addr, const char *callsign);
+extern int ax25cmp(const ax25_address *, const ax25_address *);
+extern int ax25digicmp(const ax25_digi *, const ax25_digi *);
+extern const unsigned char *ax25_addr_parse(const unsigned char *, int,
+ ax25_address *, ax25_address *, ax25_digi *, int *, int *);
+extern int ax25_addr_build(unsigned char *, const ax25_address *,
+ const ax25_address *, const ax25_digi *, int, int);
+extern int ax25_addr_size(const ax25_digi *);
+extern void ax25_digi_invert(const ax25_digi *, ax25_digi *);