Account Transaction Limit (AcctTrnLimit) is a repeating structure within Account Information (AcctInfo) that is used to convey defined transaction limits that apply to the Account overall. So it is correct that AcctTrnLimit is a member of AcctInfo. Each instance of the AcctTrnLimit structure specifies a set of attributes of the transaction which defines its ‘transaction type’, and then within that, if the limit is for an amount or a number of occurrences. A given Account could have multiple transaction types with defined Limits, which is why AcctTrnLimit a repeating structure within the AcctInfo aggregate. And a given transaction type could also have multiple defined Limits, which is why LimitType is a repeating structure within AcctTrnLimit.
For example, there could be limits defined on a given Account that control ACH withdrawals and for Checks Written (two different transaction types). ACH Withdrawals could have a Limit Type of ‘DailyMax’ with a Limit Amount, which means the sum of amounts of the given transaction type for a single day cannot exceed the Limit Amount (a monetary value), and/or it could also have a Limit Count (an integer value), which means the number of transactions of the given transaction type for a single day cannot exceed the Limit Count. And because a given transaction type could also have multiple defined Limit Types, ACH Withdrawals could also have a ‘ WeeklyMax’ with its Limit Amount and/or Limit Count. And Checks Written would have its own Limit Type(s) and within each, a Limit Amount and/or Limit Count.