An inclusion is a directive to return "child" data for a particular type associated with a parent

For example SalesTransactions would be the top level entity and queries for SalesTransactions would
normally only return the top level SalesTransactions (no items, no payments etc). Specifying an
inclusion for SalesTransactionItems would ensure that each SalesTransaction would also include
its child SalesTransactionItems

{
  "Include": true
}