The ACR/EULAR classification criteria for systemic sclerosis (SSc) entail three autoantibodies: anti-centromere antibodies (ACA). anti-topoisomerase I antibodies (ATA). and anti-RNA-polymerase III antibodies (ARA). The importance of ACA and ATA in the classification criteria is evidence based. https://lockdownsecuritycanada.shop/product-category/programming-tool/