Transaction Memos

Overview
Transactions to THORChain pass user-intent with the MEMO field on their respective chains. THORChain inspects the transaction object as well as the MEMO in order to process the transaction, so care must be taken to ensure the MEMO and the transaction are both valid. If not, THORChain will automatically refund the assets.
Different chains have different ways of adding state to a transaction. Long assets can be shortened using Asset abbreviations (below) as well as THORNames to reduce the size of destination/affiliate addresses.
Format
Memos follow the format:
FUNCTION:PARAM1:PARAM2:PARAM3:PARAM4
The function is invoked by a string, which in turn calls a particular handler in the state machine. The state machine parses the memo looking for the parameters which is simply decodes from human-readable strings. 
In addition, some parameters are optional. Simply leave them blank, but retain the : separator:
FUNCTION:PARAM1:PARAM2::
Permitted Memos
The following memos are permitted:
1.SWAP
2.Aggregator SwapOut
3.ADD Liquidity
4.WITHDRAW Liquidity
5.BOND, UNBOND & LEAVE
6.DONATE & RESERVE
7.NOOP
Swap
Perform a swap. 
SWAP:ASSET:DESTADDR:LIM:AFFILIATE:FEE
Parameter
Notes
Conditions
Payload
Send the asset to swap. 
Must be an active pool on THORChain.
SWAP
The swap handler 
also s, =
:ASSET
The asset identifier.
Can be shortened.
:DESTADDR
The destination address to send to. 
Can use THORName.
:LIM 
The trade limit ie, set 100000000 to get a minimum of 1 full asset, else a refund.
Optional
:AFFILIATE
The affiliate address. RUNE is sent to Affiliate. 
Optional. Must be THORName or THOR Address.
:FEE
The affiliate fee. Limited from 0 to 1000 Basis Points. 
Optional
Examples
SWAP:ASSET:DESTADDR simply swap
=:ASSET:DESTADDR:LIM swap with limit
s:ASSET:DESTADDR:LIM:AFFILIATE:FEE swap with limit and affiliate
=:THOR.RUNE:thor1el4ufmhll3yw7zxzszvfakrk66j7fx0tvcslym:19779138111
s:BNB/BUSD-BD1:thor15s4apx9ap7lazpsct42nmvf0t6am4r3w0r64f2:628197586176 
Add Liquidity
There are rules for adding liquidity, see the rules here and regardless of how it is added, it is subject to Impermanent Loss Protection. Also see Impermanent Loss Protection Details. 

ADD:POOL:PAIREDADDR:AFFILIATE:FEE
Parameter
Notes
Conditions
Payload
The asset to add liquidity with. 
Must be supported by THORChain.
ADD
The Add Liquidity handler.
also a +
:POOL
The pool to add liquidity to.
Can be shortened.
:PAIREDADDR
The other address to link with. If on external chain, link to THOR address. If on THORChain, link to external address. If a paired address is found, the LP is matched and added. If none is found, the liquidity is put into pending. 
Optional. If not specified, a single-sided add-liquidity action is created. 
:AFFILIATE
The affiliate address. The affiliate is added in to the pool as an LP. 
Optional. Must be THORName or THOR Address.
:FEE
The affiliate fee. Fee is allocated to the affiliate. 
Optional. Limited from 0 to 1000 Basis Points.
Examples
ADD:POOL single-sided add liquidity.  If this is a position's first add, liquidity can only be withdrawn to the same address.
+:POOL:PAIREDADDR add on both sides. 
a:POOL:PAIREDADDR:AFFILIATE:FEE add with affiliate
+:BTC.BTC:
Withdraw Liquidity
Withdraw liquidity from a pool.
A withdrawal can only be either entirely symmetric (the pool's depth ratio) or entirely asymmetric (only one asset type).
WITHDRAW:POOL:BASISPOINTS:ASSET
Parameter
Notes
Extra
Payload
Send just enough of the asset to cause the transaction to be picked up by THORChain. 
Caution Dust Limits: BTC,BCH,LTC chains 10k sats; DOGE 1m Sats; ETH 0 wei; THOR 0 RUNE. 
WITHDRAW
The withdraw handler.
Also - wd
:POOL
The pool to withdraw liquidity from.
Can be shortened.
:BASISPOINTS
Basis points (0-10000, where 10000=100%)
​
:ASSET
Assymetrical withdraw to one side.
Optional. Can be shortened. Must be either RUNE or the ASSET.
Examples
WITHDRAW:POOL:10000 dual-sided 100% withdraw liquidity.  If a single-address position, this withdraws single-sidedly instead.
-:POOL:1000 dual-sided 10% withdraw liquidity. 
wd:POOL:5000:ASSET withdraw 50% liquidity as the asset specified while the rest stays in the pool.
-:BTC.BTC:10000
DONATE & RESERVE
Donate to a pool or the RESERVE.
DONATE:POOL
Parameter
Notes
Extra
Payload
The asset to donate to a THORChain pool.
Must be supported by THORChain. Can be RUNE or ASSET.
DONATE
The donate handler.
Also %
:POOL
The pool to withdraw liquidity from.
Can be shortened.
RESERVE
Parameter
Notes
Extra
Payload
THOR.RUNE
The RUNE to credit to the RESERVE.
RESERVE
The reserve handler.
​
BOND, UNBOND & LEAVE
Perform node maintenance features. 
BOND:NODEADDR
Parameter
Notes
Extra
Payload
The asset to bond to a  Node.
Must be RUNE.
BOND
The bond handler.
Must be in Standby, or Active (but not within 12 hours of churning).
:NODEADDR
The node to bond to.
​
UNBOND:NODEADDR:AMOUNT
Parameter
Notes
Extra
Payload
None required
Use MsgDeposit
BOND
The bond handler.
​
:NODEADDR
The node to unbond from.
Must be in standby only.
:AMOUNT
The amount to unbond.
In 1e8 format.
LEAVE:NODEADDR
Parameter
Notes
Extra
Payload
None required
Use MsgDeposit
LEAVE
The LEAVE handler.
​
:NODEADDR
The node to force to LEAVE.
If in Active, forces to Leave. If in Standby, causes a 20min timer to return yggdrasil assets. 
Examples
BOND:thor1xd4j3gk9frpxh8r22runntnqy34lwzrdkazldh
LEAVE:thor18r8gnfm4qjak47qvpjdtw66ehsx49w99c5wewd
NOOP
Dev-centric functions to fix THORChain state. Caution: may cause loss of funds if not done exactly right at the right time. 
NOOP
Parameter
Notes
Extra
Payload
The asset to credit to a vault.
Must be ASSET or RUNE.
NOOP
The  noop handler.
Adds to the vault balance, but does not add to the pool.
:NOVAULT
Do not credit the vault.
Optional. Just fix the insolvency issue.
Refunds
The following are the conditions for refunds:
Condition
Notes
Invalid MEMO
If the MEMO is incorrect the user will be refunded.
Invalid Assets
If the asset for the transaction is incorrect (adding an asset into a wrong pool) the user will be refunded.
Invalid Transaction Type
If the user is performing a multi-send vs a send for a particular transaction, they are refunded.
Exceeding Price Limit
If the final value achieved in a trade differs to expected, they are refunded.
Refunds cost fees to prevent Denial of Service attacks. The user will pay the correct outbound fee for that chain.
​
Asset Notation
The following is the notation for Assets in THORChain's system:
Note: Asset.Asset denotes native asset. Asset/Asset denotes a Synthetic Asset
Examples
Asset
Notation
Bitcoin
BTC.BTC (Native)
Bitcoin
BTC/BTC (Synth)
Ethereum
ETH.ETH
USDT
ETH.USDT-0xdac17f958d2ee523a2206206994597c13d831ec7
BNB
BNB.BNB (Native)
BNB
BNB/BNB (Synth)
RUNE (BEP2)
BNB.RUNE-B1A
RUNE (NATIVE)
THOR.RUNE
Asset Abbreviations
Assets can be abbreviated using fuzzy logic. The following will all be matched appropriately. If there are conflicts then the deepest pool is matched. (To prevent attacks).
Notation
ETH.USDT
ETH.USDT-ec7
ETH.USDT-6994597c13d831ec7
ETH.USDT-0xdac17f958d2ee523a2206206994597c13d831ec7
Mechanism for Transaction Intent
Chain
Mechanism
Notes
Bitcoin
OP_RETURN
Limited to 80 bytes.
Ethereum
Smart Contract Input
Use deposit(vault, asset, amount, memo) function, where memo is string
Binance Chain
MEMO
Each transaction has an optional memo, limited to 128 bytes.
Monero
Extra Data
Each transaction can have attached extra data field, that has no limits.
Each chain will have a unique way of adding state to a transaction. Long assets can be shortened using Asset abbreviations (below) as well as THORNames to reduce the size of destination/affiliate addresses.​