if (true || item_is_critical(mitm[curr]))

            if (item_is_critical(mitm[curr]))

    "statue_reserved_1", "statue_reserved_2", "", "", "", "", "", "", "", "",
    "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
    "", "", "", "", "", "", "", "", "lava", "deep_water", "", "",
    "shallow_water", "water_stuck", "floor", "exit_hell", "enter_hell",
    "open_door", "", "", "", "", "trap_mechanical", "trap_magical", "trap_iii",

    "statue_reserved_1", "statue_reserved_2", "", "", "", "", "", "",
    "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
    "", "", "", "", "", "", "", "", "", "", "", "", "", "lava",
    "deep_water", "", "", "shallow_water", "water_stuck", "floor",
    "exit_hell", "enter_hell", "open_door", "", "", "", "",
    "trap_mechanical", "trap_magical", "trap_iii",

    "stone_stairs_down_i", "stone_stairs_down_ii", "stone_stairs_down_iii",
    "rock_stairs_down", "stone_stairs_up_i", "stone_stairs_up_ii",
    "stone_stairs_up_iii", "rock_stairs_up", "", "", "enter_dis",
    "enter_gehenna", "enter_cocytus", "enter_tartarus", "enter_abyss",
    "exit_abyss", "stone_arch", "enter_pandemonium", "exit_pandemonium",
    "transit_pandemonium", "", "", "", "builder_special_wall",
    "builder_special_floor", "", "", "", "enter_orcish_mines", "enter_hive",
    "enter_lair", "enter_slime_pits", "enter_vaults", "enter_crypt",
    "enter_hall_of_blades", "enter_zot", "enter_temple", "enter_snake_pit",
    "enter_elven_halls", "enter_tomb", "enter_swamp", "enter_shoals",
    "enter_reserved_2", "enter_reserved_3", "enter_reserved_4", "", "", "",
    "return_from_orcish_mines", "return_from_hive", "return_from_lair",
    "return_from_slime_pits", "return_from_vaults", "return_from_crypt",
    "return_from_hall_of_blades", "return_from_zot", "return_from_temple",
    "return_from_snake_pit", "return_from_elven_halls", "return_from_tomb",

    "stone_stairs_down_i", "stone_stairs_down_ii",
    "stone_stairs_down_iii", "rock_stairs_down", "stone_stairs_up_i",
    "stone_stairs_up_ii", "stone_stairs_up_iii", "rock_stairs_up", "",
    "", "enter_dis", "enter_gehenna", "enter_cocytus",
    "enter_tartarus", "enter_abyss", "exit_abyss", "stone_arch",
    "enter_pandemonium", "exit_pandemonium", "transit_pandemonium",
    "", "", "", "builder_special_wall", "builder_special_floor", "",
    "", "", "enter_orcish_mines", "enter_hive", "enter_lair",
    "enter_slime_pits", "enter_vaults", "enter_crypt",
    "enter_hall_of_blades", "enter_zot", "enter_temple",
    "enter_snake_pit", "enter_elven_halls", "enter_tomb",
    "enter_swamp", "enter_shoals", "enter_reserved_2",
    "enter_reserved_3", "enter_reserved_4", "", "", "",
    "return_from_orcish_mines", "return_from_hive",
    "return_from_lair", "return_from_slime_pits",
    "return_from_vaults", "return_from_crypt",
    "return_from_hall_of_blades", "return_from_zot",
    "return_from_temple", "return_from_snake_pit",
    "return_from_elven_halls", "return_from_tomb",

    "return_reserved_3", "return_reserved_4", "", "", "", "", "", "", "", "",
    "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
    "", "", "", "", "", "", "altar_zin", "altar_shining_one",
    "altar_kikubaaqudgha", "altar_yredelemnul", "altar_xom", "altar_vehumet",

    "return_reserved_3", "return_reserved_4", "", "", "", "", "", "",
    "", "", "", "", "", "", "", "enter_bazaar", "exit_bazaar", "", "",
    "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
    "altar_zin", "altar_shining_one", "altar_kikubaaqudgha",
    "altar_yredelemnul", "altar_xom", "altar_vehumet",

    "altar_nemelex_xobeh", "altar_elyvilon", "altar_lugonu", "altar_beogh", "",
    "", "", "", "", "", "blue_fountain", "dry_fountain_i",
    "sparkling_fountain", "dry_fountain_ii", "dry_fountain_iii",
    "dry_fountain_iv", "dry_fountain_v", "dry_fountain_vi", "dry_fountain_vii",
    "dry_fountain_viii", "permadry_fountain"

    "altar_nemelex_xobeh", "altar_elyvilon", "altar_lugonu",
    "altar_beogh", "", "", "", "", "", "", "blue_fountain",
    "dry_fountain_i", "sparkling_fountain", "dry_fountain_ii",
    "dry_fountain_iii", "dry_fountain_iv", "dry_fountain_v",
    "dry_fountain_vi", "dry_fountain_vii", "dry_fountain_viii",
    "permadry_fountain"    

    if (!is_valid_item(item))
        return (false);
    

           I. Feature names

MARKER:  A = feat:<feature_name> or timer:
         A marker ties a square on the map to a game-trigger of some
         sort (which depends on the marker and what feature it is on).
         
         The portals to the Hells in the Vestibule of Hell are each
         annotated with feature markers like this:
         MARKER: D=feat:enter_dis, G=feat:enter_gehenna
         When the horn is sounded, the stone arch at D becomes the
         portal to Dis, the arch at G becomes the portal to Gehenna,
         etc. This behaviour applies only to the Vestibule of Hell.
         Timer feature markers set a timer on a particular square;
         when time runs out, the feature at that square is changed
         (usually to floor). For instance:
         MARKER: A = timer: 500-1000
         Sets a timer that's between 500-1000 turns, inclusive, at the
         end of which whatever feature is on A gets converted to floor.
         You can specify the final feature with a feat: qualifier:
         MARKER: A = timer: 500 feat:deep_water

         This sets a timer for exactly 500 turns, and changes the
         feature to deep water at the end of it.
         Feature names used in markers must be names matching the
         names in the source code, not the descriptions as used in
         KFEAT. There's a full list of feature names at the end of this
         document.
         

I.   Feature Names
------------------
These are the feature names usable in MARKER declarations:
unseen, rock_wall, stone_wall, closed_door, metal_wall, secret_door,
green_crystal_wall, orcish_idol, wax_wall, permarock_wall,
silver_statue, granite_statue, orange_crystal_statue,
statue_reserved_1, statue_reserved_2, lava, deep_water, shallow_water,
water_stuck, floor, exit_hell, enter_hell, open_door, trap_mechanical,
trap_magical, trap_iii, undiscovered_trap, enter_shop,
enter_labyrinth, stone_stairs_down_i, stone_stairs_down_ii,
stone_stairs_down_iii, rock_stairs_down, stone_stairs_up_i,
stone_stairs_up_ii, stone_stairs_up_iii, rock_stairs_up, enter_dis,
enter_gehenna, enter_cocytus, enter_tartarus, enter_abyss, exit_abyss,
stone_arch, enter_pandemonium, exit_pandemonium, transit_pandemonium,
builder_special_wall, builder_special_floor, enter_orcish_mines,
enter_hive, enter_lair, enter_slime_pits, enter_vaults, enter_crypt,
enter_hall_of_blades, enter_zot, enter_temple, enter_snake_pit,
enter_elven_halls, enter_tomb, enter_swamp, enter_shoals,
enter_reserved_2, enter_reserved_3, enter_reserved_4,
return_from_orcish_mines, return_from_hive, return_from_lair,
return_from_slime_pits, return_from_vaults, return_from_crypt,
return_from_hall_of_blades, return_from_zot, return_from_temple,
return_from_snake_pit, return_from_elven_halls, return_from_tomb,
return_from_swamp, return_from_shoals, return_reserved_2,
return_reserved_3, return_reserved_4, enter_bazaar, exit_bazaar,
altar_zin, altar_shining_one, altar_kikubaaqudgha, altar_yredelemnul,
altar_xom, altar_vehumet, altar_okawaru, altar_makhleb,
altar_sif_muna, altar_trog, altar_nemelex_xobeh, altar_elyvilon,
altar_lugonu, altar_beogh, blue_fountain, dry_fountain_i,
sparkling_fountain, dry_fountain_ii, dry_fountain_iii,
dry_fountain_iv, dry_fountain_v, dry_fountain_vi, dry_fountain_vii,
dry_fountain_viii, permadry_fountain