diff --git a/Stellar-contract.x b/Stellar-contract.x
index 7c5fe68..d7f34b4 100644
--- a/Stellar-contract.x
+++ b/Stellar-contract.x
@@ -250,14 +250,14 @@ case NEGATIVE:
 
 enum SCContractCodeType
 {
-    SCCONTRACT_CODE_WASM = 0,
+    SCCONTRACT_CODE_WASM_REF = 0,
     SCCONTRACT_CODE_TOKEN = 1
 };
 
 union SCContractCode switch (SCContractCodeType type)
 {
-case SCCONTRACT_CODE_WASM:
-    opaque wasm<SCVAL_LIMIT>;
+case SCCONTRACT_CODE_WASM_REF:
+    Hash wasm_id;
 case SCCONTRACT_CODE_TOKEN:
     void;
 };
diff --git a/Stellar-ledger-entries.x b/Stellar-ledger-entries.x
index 9caf8bd..2616d2c 100644
--- a/Stellar-ledger-entries.x
+++ b/Stellar-ledger-entries.x
@@ -100,7 +100,8 @@ enum LedgerEntryType
     CLAIMABLE_BALANCE = 4,
     LIQUIDITY_POOL = 5,
     CONTRACT_DATA = 6,
-    CONFIG_SETTING = 7
+    CONTRACT_CODE = 7,
+    CONFIG_SETTING = 8
 };
 
 struct Signer
@@ -499,6 +500,13 @@ struct ContractDataEntry {
     SCVal val;
 };
 
+struct ContractCodeEntry {
+    ExtensionPoint ext;
+
+    Hash hash;
+    opaque code<SCVAL_LIMIT>;
+};
+
 enum ConfigSettingType
 {
     CONFIG_SETTING_TYPE_UINT32 = 0
@@ -560,6 +568,8 @@ struct LedgerEntry
         LiquidityPoolEntry liquidityPool;
     case CONTRACT_DATA:
         ContractDataEntry contractData;
+    case CONTRACT_CODE:
+        ContractCodeEntry contractCode;
     case CONFIG_SETTING:
         ConfigSettingEntry configSetting;
     }
@@ -622,6 +632,11 @@ case CONTRACT_DATA:
         Hash contractID;
         SCVal key;
     } contractData;
+case CONTRACT_CODE:
+    struct
+    {
+        Hash hash;
+    } contractCode;
 case CONFIG_SETTING:
     struct
     {
@@ -645,6 +660,7 @@ enum EnvelopeType
     ENVELOPE_TYPE_CONTRACT_ID_FROM_ED25519 = 8,
     ENVELOPE_TYPE_CONTRACT_ID_FROM_CONTRACT = 9,
     ENVELOPE_TYPE_CONTRACT_ID_FROM_ASSET = 10,
-    ENVELOPE_TYPE_CONTRACT_ID_FROM_SOURCE_ACCOUNT = 11
+    ENVELOPE_TYPE_CONTRACT_ID_FROM_SOURCE_ACCOUNT = 11,
+    ENVELOPE_TYPE_CREATE_CONTRACT_ARGS = 12
 };
 }
diff --git a/Stellar-transaction.x b/Stellar-transaction.x
index cdf108b..ba291db 100644
--- a/Stellar-transaction.x
+++ b/Stellar-transaction.x
@@ -474,23 +474,66 @@ struct LiquidityPoolWithdrawOp
     int64 minAmountB; // minimum amount of second asset to withdraw
 };
 
-enum HostFunction
+enum HostFunctionType
 {
-    HOST_FN_INVOKE_CONTRACT = 0,
-    HOST_FN_CREATE_CONTRACT_WITH_ED25519 = 1,
-    HOST_FN_CREATE_CONTRACT_WITH_SOURCE_ACCOUNT = 2,
-    HOST_FN_CREATE_TOKEN_CONTRACT_WITH_SOURCE_ACCOUNT = 3,
-    HOST_FN_CREATE_TOKEN_CONTRACT_WITH_ASSET = 4
+    HOST_FUNCTION_TYPE_INVOKE_CONTRACT = 0,
+    HOST_FUNCTION_TYPE_CREATE_CONTRACT = 1,
+    HOST_FUNCTION_TYPE_INSTALL_CONTRACT_CODE = 2
+};
+
+enum ContractIDType
+{
+    CONTRACT_ID_FROM_SOURCE_ACCOUNT = 0,
+    CONTRACT_ID_FROM_ED25519_PUBLIC_KEY = 1,
+    CONTRACT_ID_FROM_ASSET = 2
+};
+ 
+enum ContractIDPublicKeyType
+{
+    CONTRACT_ID_PUBLIC_KEY_SOURCE_ACCOUNT = 0,
+    CONTRACT_ID_PUBLIC_KEY_ED25519 = 1
+};
+
+struct InstallContractCodeArgs
+{
+    opaque code<SCVAL_LIMIT>;
+};
+
+union ContractID switch (ContractIDType type)
+{
+case CONTRACT_ID_FROM_SOURCE_ACCOUNT:
+    uint256 salt;
+case CONTRACT_ID_FROM_ED25519_PUBLIC_KEY:
+    struct 
+    {
+        uint256 key;
+        Signature signature;
+        uint256 salt;
+    } fromEd25519PublicKey;
+case CONTRACT_ID_FROM_ASSET:
+    Asset asset;
+};
+
+struct CreateContractArgs
+{
+    ContractID contractID;
+    SCContractCode source;
+};
+
+union HostFunction switch (HostFunctionType type)
+{
+case HOST_FUNCTION_TYPE_INVOKE_CONTRACT:
+    SCVec invokeArgs;
+case HOST_FUNCTION_TYPE_CREATE_CONTRACT:
+    CreateContractArgs createContractArgs;
+case HOST_FUNCTION_TYPE_INSTALL_CONTRACT_CODE:
+    InstallContractCodeArgs installContractCodeArgs;
 };
 
 struct InvokeHostFunctionOp
 {
     // The host function to invoke
     HostFunction function;
-
-    // Parameters to the host function
-    SCVec parameters;
-
     // The footprint for this invocation
     LedgerFootprint footprint;
 };
@@ -580,23 +623,37 @@ case ENVELOPE_TYPE_POOL_REVOKE_OP_ID:
 case ENVELOPE_TYPE_CONTRACT_ID_FROM_ED25519:
     struct
     {
+        Hash networkID;
         uint256 ed25519;
         uint256 salt;
     } ed25519ContractID;
 case ENVELOPE_TYPE_CONTRACT_ID_FROM_CONTRACT:
     struct
     {
+        Hash networkID;
         Hash contractID;
         uint256 salt;
     } contractID;
 case ENVELOPE_TYPE_CONTRACT_ID_FROM_ASSET:
-    Asset fromAsset;
+    struct
+    {
+        Hash networkID;
+        Asset asset;
+    } fromAsset;
 case ENVELOPE_TYPE_CONTRACT_ID_FROM_SOURCE_ACCOUNT:
     struct
     {
+        Hash networkID;
         AccountID sourceAccount;
         uint256 salt;
     } sourceAccountContractID;
+case ENVELOPE_TYPE_CREATE_CONTRACT_ARGS:
+    struct
+    {
+        Hash networkID;
+        SCContractCode source;
+        uint256 salt;
+    } createContractArgs;        
 };
 
 enum MemoType