Description
NSE modifies Part D Annexure 9 of the F&O consolidated circular to expand the Total Volume field size from char(10) to char(17) in the Final Bhav Copy (DDMM0000.md) file, effective May 9, 2026.
Summary
NSE’s Futures & Options segment has issued a partial modification to Part D Annexure 9 of the F&O consolidated circular (NSE/FAOP/67775, dated April 30, 2025). The change expands the Total Volume field (field number 12) in the Final Bhav Copy file (DDMM0000.md) from char(10) to char(17). All other fields and the overall file structure remain unchanged. The effective date for live implementation is May 9, 2026, preceded by a mock run.
Key Points
- Only one field is modified: Field 12 – Total Volume, size increased from
char(10)tochar(17) - File nomenclature (
DDMM0000.md) and all other fields remain unchanged - Change is in Part D, Annexure 9 of the F&O consolidated circular
- Reference base circular: NSE/FAOP/67775 dated April 30, 2025
- Circular Ref. No: 48/2026; Download Ref: NSE/FAOP/73824
Regulatory Changes
Partial modification to Part D of the F&O Consolidated Circular:
| Annexure | File | Field No. | Field Name | Current Size | Revised Size |
|---|---|---|---|---|---|
| 9 | DDMM0000.md | 12 | Total Volume | char(10) | char(17) |
No structural or format changes beyond the above field size expansion.
Compliance Requirements
- All members and their technology vendors who parse or ingest the Final Bhav Copy (
DDMM0000.md) file must update their systems to accommodate the expandedTotal Volumefield size (char(17)) before the effective date - Systems with fixed-width or strict-length parsing logic for field 12 are at risk of data truncation or processing errors if not updated
- Members should test their updated systems during the mock run period prior to May 9, 2026
Important Dates
- April 21, 2026 – Circular issued
- May 9, 2026 – Effective date of implementation (mock run precedes live go-live)
Impact Assessment
This is a technical operational change with moderate impact on member back-office and data systems that consume NSE’s F&O Final Bhav Copy file. The field size expansion from 10 to 17 characters for Total Volume suggests increasing trade volumes in the F&O segment have exceeded the previous capacity of the field. Members using automated data pipelines, risk systems, or reporting tools that parse this file must update their field definitions before May 9, 2026 to avoid data integrity issues. There is no change to trading rules, margins, or compliance obligations.
Impact Justification
Technical file format change affecting systems that consume F&O Final Bhav Copy data; no trading rule or compliance obligation change, but member systems processing the md file must be updated before the May 9, 2026 go-live to avoid data truncation.