> ## Documentation Index
> Fetch the complete documentation index at: https://cosmos-docs-sync-security-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# ProtocolBuffer Annotations

> This document explains the various protobuf scalars that have been added to make working with protobuf easier for Cosmos SDK application developers

This document explains the various protobuf scalars that have been added to make working with protobuf easier for Cosmos SDK application developers

## Signer

Signer specifies which field should be used to determine the signer of a message for the Cosmos SDK. This field can be used for clients as well to infer which field should be used to determine the signer of a message.

Read more about the signer field [here](/sdk/v0.50/build/building-modules/messages-and-queries).

```protobuf theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e6848d99b55a65d014375b295bdd7f9641aac95e/proto/cosmos/bank/v1beta1/tx.proto#L40
```

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
option (cosmos.msg.v1.signer) = "from_address";
```

## Scalar

The scalar type defines a way for clients to understand how to construct protobuf messages according to what is expected by the module and sdk.

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
(cosmos_proto.scalar) = "cosmos.AddressString"
```

Example of account address string scalar:

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e6848d99b55a65d014375b295bdd7f9641aac95e/proto/cosmos/bank/v1beta1/tx.proto#L46
```

Example of validator address string scalar:

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/distribution/v1beta1/query.proto#L87
```

Example of Decimals scalar:

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/distribution/v1beta1/distribution.proto#L26
```

Example of Int scalar:

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/gov/v1/gov.proto#L137
```

There are a few options for what can be provided as a scalar: `cosmos.AddressString`, `cosmos.ValidatorAddressString`, `cosmos.ConsensusAddressString`, `cosmos.Int`, `cosmos.Dec`.

## Implements\_Interface

Implement interface is used to provide information to client tooling like [telescope](https://github.com/cosmology-tech/telescope) on how to encode and decode protobuf messages.

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
option (cosmos_proto.implements_interface) = "cosmos.auth.v1beta1.AccountI";
```

## Method,Field,Message Added In

`method_added_in`, `field_added_in` and `message_added_in` are annotations to denotate to clients that a field has been supported in a later version. This is useful when new methods or fields are added in later versions and that the client needs to be aware of what it can call.

The annotation should be worded as follow:

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
option (cosmos_proto.method_added_in) = "cosmos-sdk v0.50.1";
option (cosmos_proto.method_added_in) = "x/epochs v1.0.0";
option (cosmos_proto.method_added_in) = "simapp v24.0.0";
```

## Amino

The amino codec was removed in `v0.50+`, this means there is not a need register `legacyAminoCodec`. To replace the amino codec, Amino protobuf annotations are used to provide information to the amino codec on how to encode and decode protobuf messages.

<Note>
  Amino annotations are only used for backwards compatibility with amino. New modules are not required use amino annotations.
</Note>

The below annotations are used to provide information to the amino codec on how to encode and decode protobuf messages in a backwards compatible manner.

### Name

Name specifies the amino name that would show up for the user in order for them see which message they are signing.

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
option (amino.name) = "cosmos-sdk/BaseAccount";
```

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/bank/v1beta1/tx.proto#L41
```

### Field\_Name

Field name specifies the amino name that would show up for the user in order for them see which field they are signing.

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
uint64 height = 1 [(amino.field_name) = "public_key"];
```

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/distribution/v1beta1/distribution.proto#L166
```

### Dont\_OmitEmpty

Dont omitempty specifies that the field should not be omitted when encoding to amino.

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
repeated cosmos.base.v1beta1.Coin amount = 3 [(amino.dont_omitempty)   = true];
```

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/bank/v1beta1/bank.proto#L56
```

### Encoding

Encoding instructs the amino json marshaler how to encode certain fields that may differ from the standard encoding behavior. The most common example of this is how `repeated cosmos.base.v1beta1.Coin` is encoded when using the amino json encoding format. The `legacy_coins` option tells the json marshaler [how to encode a null slice](https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/x/tx/signing/aminojson/json_marshal.go#L65) of `cosmos.base.v1beta1.Coin`.

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
(amino.encoding)         = "legacy_coins",
```

```proto theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
// Reference: https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/bank/v1beta1/genesis.proto#L23
```