diff --git a/protob/messages-bitcoin.proto b/protob/messages-bitcoin.proto
index 09173edf7..d6d9b19a1 100644
--- a/protob/messages-bitcoin.proto
+++ b/protob/messages-bitcoin.proto
@@ -204,8 +204,8 @@ message TxAck {
             optional InputScriptType script_type = 6 [default=SPENDADDRESS];    // defines template of input script
             optional MultisigRedeemScriptType multisig = 7;                     // Filled if input is going to spend multisig tx
             optional uint64 amount = 8;                                         // amount of previous transaction output (for segwit only)
-            optional uint32 decred_tree = 9;
-            optional uint32 decred_script_version = 10;
+            optional uint32 decred_tree = 9;                                    // only for Decred
+            optional uint32 decred_script_version = 10;                         // only for Decred
             optional bytes prev_block_hash_bip115 = 11;                         // block hash of previous transaction output (for bip115 implementation)
             optional uint32 prev_block_height_bip115 = 12;                      // block height of previous transaction output (for bip115 implementation)
         }
@@ -215,7 +215,7 @@ message TxAck {
         message TxOutputBinType {
             required uint64 amount = 1;
             required bytes script_pubkey = 2;
-            optional uint32 decred_script_version = 3;
+            optional uint32 decred_script_version = 3;      // only for Decred
         }
         /**
         * Structure representing transaction output
@@ -227,7 +227,7 @@ message TxAck {
             required OutputScriptType script_type = 4;      // output script type
             optional MultisigRedeemScriptType multisig = 5; // defines multisig address; script_type must be PAYTOMULTISIG
             optional bytes op_return_data = 6;              // defines op_return data; script_type must be PAYTOOPRETURN, amount must be 0
-            optional uint32 decred_script_version = 7;
+            optional uint32 decred_script_version = 7;      // only for Decred
             optional bytes block_hash_bip115 = 8;           // block hash of existing block (recommended current_block - 300) (for bip115 implementation)
             optional uint32 block_height_bip115 = 9;        // block height of existing block (recommended current_block - 300) (for bip115 implementation)
             enum OutputScriptType {