From FIXwiki

TrdType Value 23

Value	Name	Field(tag)	First introduced	Deprecated
23	SubstitutionOfFuturesForForwards	TrdType(828)	FIX.4.4

An OTC deal where the participants have agreed that the OTC deal will immediately be extinguished and replaced with a transaction in a regulated future.

[from EP84]

Notes

Error in FIX Specification:

In the Glossary (Spec volume 1) this value is incorrectly associated with the TradeCondition field.