The transactionGroup is an attribute on a TransactionType which is used to group together TransactionTypes of the same source. By setting a transactionGroup, users can quickly identify the source of the TransactionType. This is useful when you have multiple data sources for your TransactionTypes i.e. multiple custodians.
To illustrate, you could be using the alias of "Buy" to represent buy transactions in your custodian data source. You would then use a common transactionGroup (e.g. "test_nt") to group together all other transaction types in the same custodian data source (e.g. "sell", "stock_in", "subscription" etc).
Sample response for a TransactionType (see API documentation)
You would then add this transactionGroup as a source on the transaction to generate holdings.
Sample upsert transaction request (see API documentation):
2. Using the same TransactionType from multiple sources
LUSID allows users to load the same transaction type from multiple sources. For example, your IBOR and ABOR both might use a transaction type of "Sell" or "BuyToClose". These can both be mapped to the same movement in LUSID. We then link the transactionGroup on the TransactionType to the source on the transaction to see if the transaction originated in the IBOR or ABOR.