# Standard Header The [Standard Header](https://www.onixs.biz/fix-dictionary/4.4/compBlock_standard-header.html) is required on every message. :::warning > **Note:** [PossResend `<97>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_97.html) is **not supported**. Gemini will report the last sequence number that the exchange received in the header of the [Logon ``](/trading/fix/overview/session-level-messages/logon) message. The client should assume that any events the server requests to be replayed have **not** been acted upon. (See [Beginning a Session]() for details.) ::: --- ### FIELDS | Tag | Name | Req | Description | | :-: | ---------------------------------------------------------------------------- | :-: | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | 8 | [BeginString](https://www.onixs.biz/fix-dictionary/4.4/tagNum_8.html) | Y | Identifies the beginning of a new message and protocol version. Always the **first** tag in the message.

**Valid value**: `FIX.4.4` | | 9 | [BodyLength](https://www.onixs.biz/fix-dictionary/4.4/tagNum_9.html) | Y | Message length, in bytes, from right after this field up to (but **not** including) the [CheckSum `<10>`](https://www.onixs.biz/fix-dictionary/4.4/tagnum_10.html) field. Always the **second** tag in the message. | | 35 | [MsgType](https://www.onixs.biz/fix-dictionary/4.4/tagNum_35.html) | Y | Defines the message type. Always the **third** tag in the message. | | 34 | [MsgSeqNum](https://www.onixs.biz/fix-dictionary/4.4/tagNum_34.html) | Y | Sequence number of the message. | | 49 | [SenderCompID](https://www.onixs.biz/fix-dictionary/4.4/tagNum_49.html) | Y | Assigned value used to identify the firm **sending** the message. | | 43 | [PossDupFlag](https://www.onixs.biz/fix-dictionary/4.4/tagNum_43.html) | N\* | Indicates **possible retransmission** of a message with this sequence number.

**Valid values**:
`Y` = Possible duplicate
`N` = Original transmission

\*Required for a re-transmitted message. | | 52 | [SendingTime](https://www.onixs.biz/fix-dictionary/4.4/tagNum_52.html) | Y | Time of message transmission (always in UTC). | | 56 | [TargetCompID](https://www.onixs.biz/fix-dictionary/4.4/tagNum_56.html) | Y | Assigned value used to identify the firm **receiving** the message. | | 115 | [OnBehalfOfCompID](https://www.onixs.biz/fix-dictionary/4.4/tagNum_115.html) | N\* | Assigned value used to identify the **originating firm** if the message was delivered by a third party (e.g., an OMS or OEMS). **Required** if an OMS/OEMS is submitting/canceling orders on behalf of another Gemini account.

Not used or supported in Market Data or single-party Order Entry or Drop Copy.

**Third-party order entry** usage: See [Order Entry: Third Party Support](/trading/fix/order-entry/third-party-support) for details.

Third-party support for Drop Copy **does not** use [OnBehalfOfCompID `<115>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_115.html) in the header. (See [Drop Copy: Third Party Support](/trading/fix/drop-copy/party-ids-&-roles/third-party-support) for details.) | | 128 | [DeliverToCompID](https://www.onixs.biz/fix-dictionary/4.4/tagNum_128.html) | N\* | Used in **Execution Reports** only. Not used or supported in Market Data, single-party Order Entry, or Drop Copy.

The customer's **Gemini account identifier** is returned in [DeliverToCompID `<128>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_128.html) on Execution Reports.

Third-party support for Drop Copy **does not** use [DeliverToCompID `<128>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_128.html) in the header. (See [Drop Copy: Third Party Support](/trading/fix/drop-copy/party-ids-&-roles/third-party-support) for details.) | | 122 | [OrigSendingTime](https://www.onixs.biz/fix-dictionary/4.4/tagNum_122.html) | N\* | Original time of message transmission (in UTC) when transmitting orders as the result of a resend request. | > \* Required for a re-transmitted message.