From FIXwiki

AllocType Value 6

Value	Name	Field(tag)	First introduced	Deprecated
6	BuysideReadyToBook	AllocType(626)	FIX.4.3	FIX.4.2

Buyside Ready-To-Book - Combined Set of Orders (Replaced)

Notes

Error in FIX Specification:

Deprecated before it was introduced!