A booking flow that you can use to sell tickets on Line-Up.
This could be the flow used by your Box Office or for your Online Checkout.
If it's for your Box Office and you have multiple venues or users, you can create specific Purchase Flows and restrict them to certain Channels, Events or Terminals.
If it's for your Online Checkout, you can create a Purchase Channel which has its own URL link. You can copy this link and send to customers to make purchases through that Channel.