# Standard message header

Standard header is a set of fields that is part of every message. 

It contains information that is common to all messages and provides essential details for processing and interpreting the subsequent message.

| Tag       | Name                | Type           | Required                         | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| --------- | ------------------- | -------------- | -------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **8**     | `BeginString`       | `String`       | **yes**                          | This field indicates the FIX protocol version being used. For [FIX 4.4](https://www.onixs.biz/fix-dictionary/4.4/index.html), the value is: `FIX.4.4.`. Must be the **first** field in the message.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| **9**     | `BodyLength`        | `Length`       | **yes**                          | The length of the message body in bytes, excluding the `BeginString` and `BodyLength` fields. It represents the total length of the message. Must be the **second** field in the message.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| **35**    | `MsgType`           | `String`       | **yes**                          | A three-character code representing the message type. Each type of the FIX message (e.g., [**`D` (New Order - Single)**](/docs/guides/exchange-fix-api/trading-fix-api/supported-fix-messages/fix-application-level-messages/message-D-new-order-single), [**`8` (Execution Report)**](/docs/guides/exchange-fix-api/trading-fix-api/supported-fix-messages/fix-application-level-messages/message-8-execution-report), [**`F` (Order Cancel Request)**](/docs/guides/exchange-fix-api/trading-fix-api/supported-fix-messages/fix-application-level-messages/message-F-order-cancel-request), [**`V` (Market Data Request)**](/docs/guides/exchange-fix-api/market-data-fix-api/supported-fix-messages/fix-application-level-messages/message-v-market-data-request) etc.) is uniquely identified by the `MsgType` field. Must be the **third** field in the message. |
| **49**    | `SenderCompID`      | `String`       | **yes**                          | The identifier for the sender of the message. It represents the unique identifier of the trading system or entity sending the message.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| **56**    | `TargetCompID`      | `String`       | **yes**                          | The identifier for the target of the message. It represents the unique identifier of the trading system or entity receiving the message.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| **34**    | `MsgSeqNum`         | `SeqNum`       | **yes**                          | A unique number assigned to each message by the sender. It increments with each subsequent message sent.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| **43**    | `PossDupFlag`       | `Boolean`      | **no**                           | Indicates possible retransmission of the message with this sequence number. Required for retransmitted messages. <br/><br/>Supported values:<br/><ul><li>`Y` - Possible duplicate</li><li>`N` - Original transmission</li></ul>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| **97**    | `PossResend`        | `Boolean`      | **no**                           | Indicates that message may contain information that has been sent under another sequence number. <br/><br/>Supported values:<br/><ul><li>`Y` - Possible resend</li><li>`N` - Original transmission</li></ul>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| **52**    | `SendingTime`       | `UTCTimestamp` | **yes**                          | The timestamp indicating when the message was created and sent. <br/><br/>It is in UTC (Coordinated Universal Time). <br/>The format is: `YYYYMMDD-HH:MM:SS.sss`.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| **122**   | `OrigSendingTime`   | `UTCTimestamp` | **no***                          | An optional field that can be used to carry the original sending time of the message when the message is being resent or retransmitted. <br/><br/>*Required for message resent as a result of a [**`2` Resend Request**](/docs/guides/exchange-fix-api/market-data-fix-api/supported-fix-messages/fix-session-level-messages/message-2-resend-request).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |

For more details, see [`FIX 4.4 : StandardHeader` in the FIX 4.4 documentation](https://www.onixs.biz/fix-dictionary/4.4/compBlock_StandardHeader.html).