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--- faq:resend_request [2025/01/16 13:19] – [Sample Messages] rob
+++ faq:resend_request [2025/01/16 13:32] (current) – rob
@@ Line 1: / Line 1: @@
 ===== Resend Request =====
-**Resend Request** allows a receiving application to ask for the retransmission of previously sent messages. The requested messages are specified with a range of sequence numbers, defined by **BeginSeqNo** (Tag 7) and **EndSeqNo** (Tag 16). To request a single message, set **BeginSeqNo** equal to **EndSeqNo**. Setting **EndSeqNo** to zero (0) indicates that the range ends with the message of the highest sequence number (i.e., the last message sent).
+===== Message Range Replay =====
-==== Common Use Cases ====
+With the Resend Request message, a receiving application asks for the retransmission of previously sent messages. The previously sent messages span over an input range of sequence numbers. The input range is specified with **BeginSeqNo** (Tag 7) and **EndSeqNo** (Tag 16). To request only one message, **BeginSeqNo** is set equal to **EndSeqNo**. The specification of zero (0) for **EndSeqNo** indicates that the requested range would end with the sent message of highest sequence number (i.e. the last message sent).
-Resend Request messages are commonly encountered under the following conditions:
-  * A sequence number gap is detected.
-  * A message has been lost by a receiving application.
-  * As part of the re-initialization process for an out-of-sequence condition.
-==== Proper Response ====
+Resend Request messages are commonly encountered in the following conditions:
-A proper response to a Resend Request includes all application messages (except for MarketData Snapshot and Security Definition) but excludes administrative messages (except for Reject). The resending application may choose not to resend certain messages (e.g., NewOrder) if it deems them risky or if they fall outside an acceptable time window. All resent messages must be labeled as Possible Duplicates (i.e., Tag 43=Y). The T4 FIX API will honor all Possible Duplicates received from the client. If gaps exist in the resend message lot, **Sequence Reset** messages may be received to fill these gaps. This is common when administrative messages are excluded from the resend lot.
+  * Sequence number gap is detected
+  * A message has been lost by a receiving application
+  * Part of the re-initialization process for an out-of-sequence condition
+A proper response for a Resend Request includes all the application messages (with the exception of [[MarketData Snapshot FullRefresh|MarketData Snapshot]] and [[Security Definition|Security Definition]]) but no administrative messages (with the exception of [[Reject|Reject]]). The resending application may decide not to resend specific messages (e.g. NewOrder) if it considers it risky or the messages would be resent out of an acceptable time window. All messages (resent by the application honoring the Resend Request) must be labeled as a Possible Duplicate (i.e. Tag 43=Y). The T4 FIX API will honor all Possible Duplicates received from the client. If message gaps exist in the resend message lot, [[Sequence Reset|Sequence Reset]] messages can be received to fill the sequence number gap. This is a common occurrence when administrative messages are excluded from the resend lot.
+===== Message Dictionary =====
-==== Message Dictionary ====
 ^ Tag ^ Field Name ^ Req'd ^ Comments ^
-| Standard Header | Y | MsgType = 2 |
+|   | **[[Standard Header]]** | Y | MsgType = 2 |
-| 7 | BeginSeqNo | Y | Message sequence number of the first message in the range to be resent. |
+| 7 | BeginSeqNo | Y | Message sequence number of first message in range to be resent |
-| 16 | EndSeqNo | Y | Message sequence number of the last message in the range to be resent. If requesting a single message, **BeginSeqNo** = **EndSeqNo**. If requesting all messages after a specific message, **EndSeqNo** = "0" (representing infinity). |
+| 16 | EndSeqNo | Y | Message sequence number of last message in range to be resent. If request is for a single message, BeginSeqNo = EndSeqNo. If request is for all messages subsequent to a particular message, EndSeqNo = "0" (representing infinity). |
-| Standard Trailer | Y | |
+|   | **[[Standard Trailer]]** | Y |
+===== Sample Messages =====
-==== Sample Messages ====
 <code>
 Resend Request - All messages starting at sequence number 12: