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--- developers:fixapi:standardtrailer [2025/09/12 01:39] – chad
+++ developers:fixapi:standardtrailer [2025/09/17 01:18] (current) – [Example] chad
@@ Line 1: / Line 1: @@
-====== Standard Trailer ======
+====== STANDARD TRAILER ======
-All messages (administrative or application) are terminated by the Standard Trailer. The trailer segregates messages and contains the three-digit character representation of the Checksum value (**Tag 10**).
+The Standard Trailer terminates all FIX messages with a checksum for message integrity.
-===== Standard Trailer Dictionary =====
+===== Message Specification =====
-^ Tag  ^ Field Name ^ Req'd ^ Comments                                       |
-| 10   | CheckSum   | Y     | Checksum for current message. Always unencrypted and last field of the current message. |
+**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 =====
+<code>
+=FIX.4.2|9=73|35=0|49=SENDER|56=TARGET|34=1|52=20120101-12:00:00.000|10=215|
+                                                                      ^^^^^^
+                                                                     Checksum
+</code>
+===== Notes =====
+  * Always unencrypted
+  * Must be the last field
+  * Exactly 3 characters (pad with zeros)
+  * Delimiter (SOH) follows checksum