# Uniqueness of ClOrdId

**URL:** <https://forum.fixtrading.org/t/uniqueness-of-clordid/2455>\
**Category:** General Q&A\
**Tags:** general-qa, xid\_166117, imported\
**Created:** [December 14, 2000, 9:44am UTC](https://forum.fixtrading.org/t/uniqueness-of-clordid/2455 "2000-12-14T09:44:00Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![fplpo\_x](https://avatars.discourse-cdn.com/v4/letter/f/7ab992/32.png) [@fplpo\_x](https://forum.fixtrading.org/u/fplpo_x)\
**Post date:** [December 14, 2000, 9:44am UTC](https://forum.fixtrading.org/t/uniqueness-of-clordid/2455/1 "2000-12-14T09:44:00Z")

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Imported from previous forum

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**Author:** ![fplpo\_x](https://avatars.discourse-cdn.com/v4/letter/f/7ab992/32.png) [@fplpo\_x](https://forum.fixtrading.org/u/fplpo_x)\
**Post date:** [December 14, 2000, 9:44am UTC](https://forum.fixtrading.org/t/uniqueness-of-clordid/2455/2 "2000-12-14T09:44:00Z")

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[original email was from Bernt Sanden - [bernt.sanden@omgroup.com](mailto:bernt.sanden@omgroup.com) ]  
Hi,

The definition of the ClOrdId tag says that:

"Unique identifier for Order as assigned by institution. Uniqueness must be guaranteed within a single trading day"

The uniqueness is supposed to be guaranteed by  
the institution. Should the other party, i.e. the broker or the exchange reject messages, e.g. a new order single, that contains a ClOrdId that is not unique?

In this case a FIX engine for example must keep track of all orders submitted during a day to be able to reject orders with not unique values of ClOrdId. This does not seem to be a good idea.

Regards, Bernt Sandén

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**Author:** ![scott.atwell](https://avatars.discourse-cdn.com/v4/letter/s/51bf81/32.png) [@scott.atwell](https://forum.fixtrading.org/u/scott.atwell)\
**Post date:** [December 14, 2000, 12:10pm UTC](https://forum.fixtrading.org/t/uniqueness-of-clordid/2455/3 "2000-12-14T12:10:00Z")

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See D22 in Appendix D - Order State Change Matrices in the FIX 4.2 spec. Note that the "reject" is an ExecutionRpt with ExecType of Rejected vs. a Session-level Reject message, thus the FIX engine is not responsible for tracking every ClOrdID, rather the order handler business-level processing system which interacts with the FIX engine would be.

\> Hi,  
\>  
\> The definition of the ClOrdId tag says that:  
\>  
\> "Unique identifier for Order as assigned by institution. Uniqueness must be guaranteed within a single trading day"  
\>  
\> The uniqueness is supposed to be guaranteed by  
\> the institution. Should the other party, i.e. the broker or the exchange reject messages, e.g. a new order single, that contains a ClOrdId that is not unique?  
\>  
\> In this case a FIX engine for example must keep track of all orders submitted during a day to be able to reject orders with not unique values of ClOrdId. This does not seem to be a good idea.  
\>  
\> Regards, Bernt Sandén  
\>