CREDIT cards, share certificates and even some high-yield variety seeds carry them as proof of authenticity. So do a host of well-known brands, traditional targets for the counterfeiter. Ray-Ban sunglasses, M'escos shoes, Quickfix adhesive, Surya Roshni tube fittings, Durobord plywood and Kores office stationery--they've all taken to wearing their bonafides on the sleeves. Identity cards issued by the Election Commission and marksheets of the Gujarat Secondary Education Board are sporting them. And driving licences in Delhi will soon have them.