CST exemption for SEZ units: Form I certifies qualifying purchases and prevents duplicate non liability claims. Form I prescribes the certificate mechanism for claiming CST exemption by SEZ units, requiring SEZ dealer and seller identification, tax registration details, Development Commissioner-approved goods description, invoice particulars, and two certifications: one that goods were purchased for SEZ activities (manufacture/processing/use/export/development, operation and maintenance) and a second that non-liability has not been claimed or certified elsewhere; the form requires verification by an authorised signatory and specifies retention and filing of copies.