olemus
ISO 22300:
toodete ja teenuste otse organisatsioonile (tavaliselt lepingulise korraldusega) tarnija
= provider of products and services directly to an organization usually through a contractual arrangement

ülevaateid
https://www.techtarget.com/searchitchannel/definition/tier-1-vendor
https://www.time-matters.com/emergency-logistics-glossary/tier-1-supplier/
https://www.brightest.io/tier-suppliers/
https://www.goldfields.com/supplier-classification.php