/usr/lib/interchange/standard/include/checkout/ is in interchange-cat-standard 5.7.7-2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/interchange/standard/include/checkout/billing_address
/usr/lib/interchange/standard/include/checkout/initialization
/usr/lib/interchange/standard/include/checkout/login_form
/usr/lib/interchange/standard/include/checkout/mailing_status
/usr/lib/interchange/standard/include/checkout/new_browser_payment
/usr/lib/interchange/standard/include/checkout/new_browser_payment_multi
/usr/lib/interchange/standard/include/checkout/old_browser_payment
/usr/lib/interchange/standard/include/checkout/old_browser_payment_multi
/usr/lib/interchange/standard/include/checkout/payment_select
/usr/lib/interchange/standard/include/checkout/payment_select_multi
/usr/lib/interchange/standard/include/checkout/shipping_address
/usr/lib/interchange/standard/include/checkout/shopping_cart
/usr/lib/interchange/standard/include/checkout/tax_popup