Get transactionala data-reframework

I am starting with advanced training in academy and couldn’t understand what the below paragraph actually means?

"For a linear process (not repetitive), set out_TransactionItem only for in_TransactionNumber 1 - first and only transaction.

If the process is repeatable, set io_TransactionData once for in_TransactionNumber 1, then assign a new out_TransactionItem by using the in_TransactionNumber to index io_TransactionData. Be aware that, at the end of the io_TransactionData collection, it is your responsibility to set out_TransactionItem to Nothing, thus ending the process."

What is repeatable and non-repeatable process?

Linear process means if your workflow runs only once (only one transaction). That means get transaction and process transaction executes only once. Which is non-repeatable.

Repeatable process is get transaction and process transaction repeats for all the transaction items. For example if you have 10 transactions, the process runs 10 times (get transaction and process transaction repeats 10 times) which is repeatable process.