However, I've recently noticed that there's a small issue with how some of that information can be displayed in the shop owner's admin. The line breaks are displayed properly in the cart, email notifications, and customer-facing order page. But in the Shopify admin the line breaks are removed.
So, the customer would enter this:
Happy Valentine's Day!But the shop owner sees:
Love,
Zak
Happy Valentine's Day! Love, Zak
This doesn't happen with cart attributes, though, so I've come up with a workaround to preserve those line breaks by assigning line item properties to unique cart attributes:
When you cycle through the line item properties to display them on the cart page, you also add them to a hidden cart attribute input element (in this case a textarea element). When the customer checks out, the values are displayed on the Admin Orders page as both line item properties and also cart notes.