An "Account World" is something that is defined by the "House" of a Bricknode Broker-instance. Accounts of certain worlds are then used in the configuration of Bricknode Broker, which is a very dynamic concept. The default setup contains two account worlds, which are:
Custody Accounts (Key: HouseCustodyAccount)
System Accounts (There are a number of keys since a system account can have a number of different rules, for example the most basic is a Holding Account while a more complex type is the Investment Savings Account with the key ISKAccount)
Custody Accounts are reflecting an account that exists with an external financial institution and this account world can be defined as "External" while the System Accounts are owned by the Bricknode Broker system and operated by the House and can be defined as "Internal".
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