STANDARD TRAILER
The Standard Trailer terminates all FIX messages with a checksum for message integrity.
Message Specification
Required in all messages
| Tag | Field Name | Type | Req'd | Description |
|---|---|---|---|---|
| 10 | CheckSum | String | Y | Three-digit checksum (always last field) |
Checksum Calculation
- Sum all bytes in message (excluding checksum field)
- Modulo 256 of sum
- Format as three-digit string with leading zeros
Example
8=FIX.4.2|9=73|35=0|49=SENDER|56=TARGET|34=1|52=20120101-12:00:00.000|10=215|
^^^^^^
Checksum
Notes
- Always unencrypted
- Must be the last field
- Exactly 3 characters (pad with zeros)
- Delimiter (SOH) follows checksum