-route_check_dls(uschar *rname, uschar *type, uschar *list, tree_node
- **anchorptr, unsigned int *cache_bits, int listtype, uschar *domloc,
- uschar **ldata, BOOL caseless, uschar **perror)
+route_check_dls(uschar *rname, uschar *type, const uschar *list,
+ tree_node **anchorptr, unsigned int *cache_bits, int listtype,
+ const uschar *domloc, const uschar **ldata, BOOL caseless, uschar **perror)