System fields in entities

Hi

Is it possible to allow ax system fields in Entity definitions?

We are trying to use Entities to export data from Ax to an external datawarehouse using BOYD, and we would like to export a set of transaction data. But transaction data (eg InventTrans) has no natural key. When I try to create RecId as part of the Entity (by adding it so it is called RecId1), it is placed on my entity view in the database, but the ax core omits these when it creates the staging table in BOYD (when publishing the Entity).

Is there any way it is possible to include these fields?

If not - are we going the wrong way regarding exporting transaction data from Ax?

BR Carsten