Document Identification Number recognition: eOffice Issue number deemed DIN for public option communications; DIN required otherwise. Communications dispatched using the public option in CBIC's eOffice application bearing a verifiable electronically generated Issue number shall be deemed to carry the Document Identification Number (DIN) and be treated as valid; officers must accurately populate metadata for verification. The DIN utility must still be used and quoted for communications not sent via eOffice public option or lacking a verifiable Reference Number (RFN) from the GST common portal.