}else if( fossil_strcmp(zTag, "prev")==0 
                || fossil_strcmp(zTag, "previous")==0 ){
        zUuid = db_text(0, "SELECT uuid FROM blob WHERE rid="
                           "(SELECT pid FROM plink WHERE cid=%d AND isprim)",
                           vid);
      }else if( fossil_strcmp(zTag, "next")==0 ){
        zUuid = db_text(0, "SELECT uuid FROM blob WHERE rid="
                           "(SELECT cid FROM plink WHERE pid=%d AND isprim"
                           "  ORDER BY mtime DESC)",
                           "(SELECT cid FROM plink WHERE pid=%d"
                           "  ORDER BY isprim DESC, mtime DESC)",
                           vid);
      }
    }
  }
  return zUuid;
}