Some sales channels allow customers to specific specific customizations or instructions for line items they add to their carts upon checkout. This is often referred to as line item customizations and is controlled by your sales channel directly.
Often, this is used for differentiating aspects of items you may not necessarily track stock in, such as grade or quality.
When provided by your sales channel, SKULabs can import this data to show during the picking process and typically appears as a "Customization" in red text beneath the line item:
By default, most sales channels like Shopify support line item customizations as long as they are present on the order in the channel itself. In Shopify's case, these are called "line item properties".
BigCommerce
To import order line-items with the correct customization metadata from BigCommerce, visit your store's settings, then scroll to the Access credentials & integration settings panel, and enter the "display names" of the product's optional option sets from Big Commerce (e.g. "Engraving") under the "Customization Option Names" section.
Note: Provide the "display names" of the product options, NOT the actual "values" of product option (e.g. "medium").