diff --git a/models/ActivityLevel.json b/models/ActivityLevel.json
new file mode 100644
index 0000000..7cd5ef5
--- /dev/null
+++ b/models/ActivityLevel.json
@@ -0,0 +1,9 @@
+{
+  "type": "string",
+  "description": "The activity level of a trade good. If the good is an import, this represents how strong consumption is for the good. If the good is an export, this represents how strong the production is for the good.",
+  "enum": [
+    "WEAK",
+    "GROWING",
+    "STRONG"
+  ]
+}
\ No newline at end of file
diff --git a/models/MarketTradeGood.json b/models/MarketTradeGood.json
index 7319318..414454d 100644
--- a/models/MarketTradeGood.json
+++ b/models/MarketTradeGood.json
@@ -5,20 +5,25 @@
       "type": "string",
       "description": "The symbol of the trade good."
     },
+    "type": {
+      "type": "string",
+      "description": "The type of trade good (export, import, or exchange).",
+      "enum": [
+        "EXPORT",
+        "IMPORT",
+        "EXCHANGE"
+      ]
+    },
     "tradeVolume": {
       "type": "integer",
-      "description": "The typical volume flowing through the market for this type of good. The larger the trade volume, the more stable prices will be.",
+      "description": "This is the maximum number of units that can be purchased or sold at this market in a single trade for this good. Trade volume also gives an indication of price volatility. A market with a low trade volume will have large price swings, while high trade volume will be more resilient to price changes.",
       "minimum": 1
     },
     "supply": {
-      "type": "string",
-      "description": "A rough estimate of the total supply of this good in the marketplace.",
-      "enum": [
-        "SCARCE",
-        "LIMITED",
-        "MODERATE",
-        "ABUNDANT"
-      ]
+      "$ref": "./SupplyLevel.json"
+    },
+    "activity": {
+      "$ref": "./ActivityLevel.json"
     },
     "purchasePrice": {
       "type": "integer",
@@ -33,6 +38,7 @@
   },
   "required": [
     "symbol",
+    "type",
     "tradeVolume",
     "supply",
     "purchasePrice",
diff --git a/models/ShipyardShip.json b/models/ShipyardShip.json
index cbb6c74..4f868a8 100644
--- a/models/ShipyardShip.json
+++ b/models/ShipyardShip.json
@@ -12,14 +12,10 @@
       "type": "string"
     },
     "supply": {
-      "type": "string",
-      "description": "A rough estimate of the total supply of this good in the marketplace.",
-      "enum": [
-        "SCARCE",
-        "LIMITED",
-        "MODERATE",
-        "ABUNDANT"
-      ]
+      "$ref": "./SupplyLevel.json"
+    },
+    "production": {
+      "$ref": "./ActivityLevel.json"
     },
     "purchasePrice": {
       "type": "integer"
diff --git a/models/SupplyLevel.json b/models/SupplyLevel.json
new file mode 100644
index 0000000..f9f0831
--- /dev/null
+++ b/models/SupplyLevel.json
@@ -0,0 +1,11 @@
+{
+  "type": "string",
+  "description": "The supply level of a trade good.",
+  "enum": [
+    "SCARCE",
+    "LIMITED",
+    "MODERATE",
+    "HIGH",
+    "ABUNDANT"
+  ]
+}
\ No newline at end of file