id and the module allows the users involved to autonomously claim tokens in the temporal window between the StartHeight and the EndHeight blocks.Merkle Tree. Thanks to the features of these data structure (i.e., a binary tree where each non-leaf node is the hash of its childs) they are particularly efficient in space usage and during the verification process (as explained in the Verification process).uint64stringint64actual block height + 100000.int64start_height and lower than a maximum value of start_height + 5000000.stringdenom of the token to drop.stringamount of token to drop.stringstringmerkledrop module keeps track of LastMerkledropId, Merkledrops, Indexes and Parameters.uint64, automatically incremented everytime a new merkledrop is created;denom of the token to drop;amount of token to drop;msgs) are objects that trigger state transitions. Messages are wrapped in transactions (txs) that clients submit to the network. The BitSong SDK wraps and unwraps merkledrop module messages from transactions.MsgCreate message is used to create a new merkledrop. It takes as input Owner, MerkleRoot, StartHeight, EndHeight, and Coin. The value of the block height at which the drop become available (the starting block) must be greater or equal to the block height where the transaction is included. For this reason, if the users select 0 as StartHeight it will be automatically set to the current block height (the one where the transaction is included). Moreover, there exists an upper bound for this value, that corresponds to the value of the actual block height + 100000. This choice derives from a design pattern that avoid the generation of spam merkledrop. At the same time, the EndHeight value, which corresponds to the block height where the merkledrop can be considered expired and the withdrawal is executed if part of the tokens were not claimed. This value must be greater than the StartHeight and lower than a maximum value of StartHeight + 5000000. The Coin is made up of the denom of the token to distribute and the amount, which corresponds to the sum of all the tokens to drop. Once the module has verified that the owner address is valid and that the merkletree root is a hexadecimal character string, it deduct the creation fee from the owner wallet and send the coin (the amount of token to drop), from the owner address to the module. At this point, the LastMerkleDropId is increased and the merkledrop is created, by assigning zero to the claimed value (since at the creation time, no one claimed any token). They are added three indexes:merkledrop_id;owner;end_height.EventCreate is emitted at the end of the creation process.MsgClaim message is used to claim tokens from an active merkledrop. It takes as input Sender, MerkledropId, Index, the Amount to claim, and a list of Proofs. In such a scenario, verified the validity of the sender address and the existence of the merkledrop by the ID, if the airdrop is currently active (i.e., its start block height is lower than the current block height and its end block height is greater than the current one), the module verifies if the sender already claimed his tokens (by querying at an index). In case he didn't, the module proceeds retriving the merkletree root for the merkledrop from the chain and verifies the proofs (as described in the verification process). After tese verifications, the module only checks if the coin the sender wants to claim are available, and send those tokens from the module to the sender wallet. At this point, the claim is stored through its index, the claimed tokens are added to the actually claimed amount and, if all the drops are claimed with this operation, the merkledrop is cleaned by the state. An event of type EventClaim is emitted at the end of the claim process.EndHeight (i.e., the block height at which the airdrop expires), the module can verify at each block if there is any expired merkledrop at that particular time. To perform the operations, the module is able to retrive the the merkledrops ids by the EndHeight and to process those drops. In particular, for each retrived merkledrop they are executed the withdraw of the unclaimed tokens and then, the merkledrop is cleaned by the state.EndHeight block the merkledrop is still in the store, it means that not all the tokens were claimed. For this reason, the module automatically performs a withdraw of the unclaimed tokens to the owner wallet. In particular, the module verifies if the total amount is lower than the claimed amount, calculates the balance as the unclaimed tokens (i.e., the total amount - the claimed one). This amount is sent to the owner wallet and a corresponding event of type EventWithdraw is emitted.owner, all the indexes linked to its id are deleted together with the merkledrop object in the store./bitsong.merkledrop.v1beta1.MsgCreate/bitsong.merkledrop.v1beta1.MsgClaimtransactions commands allow users to create and claim for merkledrops.query commands allow users to query the merkledrop module.