# update-symbol (/docs/tx/update-symbol)

Cosmetic call for the subnet owner (or root): changes the short ticker
shown for the subnet's alpha token in wallets, explorers, and CLIs.
Symbols are not arbitrary strings — the chain keeps a fixed catalog of
roughly 439 predefined symbols, and anything outside it is rejected
with `SymbolDoesNotExist`. A symbol already taken by another subnet
is rejected with `SymbolAlreadyInUse`. No economic effect — balances,
stake, and emissions are untouched.

| Signer    | Origin       | Pallet          | Wraps                                                                                           |
| --------- | ------------ | --------------- | ----------------------------------------------------------------------------------------------- |
| `coldkey` | subnet owner | SubtensorModule | [`SubtensorModule.update_symbol`](/code/pallets/subtensor/src/macros/dispatches.rs#L1719-L1736) |

## Parameters [#parameters]

| Parameter | Type    | Required | Description                                                                                       |
| --------- | ------- | -------- | ------------------------------------------------------------------------------------------------- |
| `netuid`  | integer | yes      | Subnet whose symbol to change; the signer must be its owner.                                      |
| `symbol`  | string  | yes      | New token symbol; must be one of the chain's predefined symbols and not in use by another subnet. |

Address parameters (`--hotkey`, `--coldkey`, `--dest`, ...) accept a raw ss58
address, an address-book or proxy-book name, or a local wallet/hotkey name.

## CLI [#cli]

Preview with `--dry-run` (shows fee, effects, and policy result without
submitting), then submit:

```bash
btcli tx update-symbol \
  --netuid <int> \
  --symbol <value> --dry-run
btcli tx update-symbol \
  --netuid <int> \
  --symbol <value> -w my_coldkey
```

## Python [#python]

```python
import bittensor as bt
from bittensor.wallet import Wallet

wallet = Wallet(name="my_coldkey", hotkey="my_hotkey")
intent = bt.UpdateSymbol(netuid=1, symbol="...")

sub = bt.Subtensor()
plan = sub.plan(intent, wallet)   # fee, effects, policy — no submission
result = sub.execute(intent, wallet)
if not result.success:
    print(result.error.code, result.error.remediation)
```

(`bt.Subtensor` is also the async client — `async with bt.Subtensor() as client:`
— see [The client](/docs/concepts/client).) Or build the intent by op name, as
an agent would:

```python
result = sub.execute_tool("update_symbol", {...}, wallet)
```

## On-chain implementation [#on-chain-implementation]

`SubtensorModule.update_symbol` — [`pallets/subtensor/src/macros/dispatches.rs#L1721`](/code/pallets/subtensor/src/macros/dispatches.rs#L1719-L1736):

```rust
#[pallet::call_index(112)]
#[pallet::weight(<T as crate::pallet::Config>::WeightInfo::update_symbol())]
pub fn update_symbol(
    origin: OriginFor<T>,
    netuid: NetUid,
    symbol: Vec<u8>,
) -> DispatchResult {
    Self::ensure_subnet_owner_or_root(origin, netuid)?;
    ensure!(Self::if_subnet_exist(netuid), Error::<T>::SubnetNotExists);

    Self::ensure_symbol_exists(&symbol)?;
    Self::ensure_symbol_available(&symbol)?;

    TokenSymbol::<T>::insert(netuid, symbol.clone());

    Self::deposit_event(Event::SymbolUpdated { netuid, symbol });
    Ok(())
}
```

Delegates to [`ensure_subnet_owner_or_root`](/code/pallets/subtensor/src/utils/misc.rs#L12), [`if_subnet_exist`](/code/pallets/subtensor/src/subnets/subnet.rs#L39), [`ensure_symbol_exists`](/code/pallets/subtensor/src/subnets/symbols.rs#L960).

Every file is browsable under [/code](/code) exactly as built into the runtime, or as plain text under `/code/raw/<path>` (index: [`/code/index.json`](/code/index.json)).