diff --git a/nml/actions/action0properties.py b/nml/actions/action0properties.py
index c32314cc..62890fcb 100644
--- a/nml/actions/action0properties.py
+++ b/nml/actions/action0properties.py
@@ -1263,6 +1263,8 @@ def check_accept(acp):
     "units_of_cargo":            {"num": 0x1B, "size": 2, "string": 0xDC},
     "items_of_cargo":            {"num": 0x1C, "size": 2, "string": 0xDC},
     "capacity_multiplier":       {"num": 0x1D, "size": 2, "unit_conversion": 0x100},
+    "town_production_effect":    {"num": 0x1E, "size": 1},
+    "town_production_multiplier":{"num": 0x1F, "size": 2, "unit_conversion": 0x100},
 }
 # fmt: on
 
diff --git a/nml/global_constants.py b/nml/global_constants.py
index ef5b43cf..8b28ee3e 100644
--- a/nml/global_constants.py
+++ b/nml/global_constants.py
@@ -907,6 +907,11 @@ def constant_number(name, info, pos):
     "TOWNGROWTH_FOOD"                       : 0x0B,
     "TOWNGROWTH_NONE"                       : 0xFF,
 
+    # Town production effect on cargo
+    "TOWNPRODUCTION_PASSENGERS"             : 0x00,
+    "TOWNPRODUCTION_MAIL"                   : 0x02,
+    "TOWNPRODUCTION_NONE"                   : 0xFF,
+
     # Cargo callbacks
     "CARGO_CB_PROFIT"                       : 0x01,
     "CARGO_CB_STATION_RATING"               : 0x02,