---
name: Serial numbers from DAT data, not filenames
description: Design decision - always extract real serial numbers from DAT record data, never rely on 8.3 encoded filenames. Discussed with John Lehman 2026-03-27.
type: feedback
---

Always pull serial numbers from the DAT record data (e.g., "178439-1","02-09-2026"), not from filenames. DOS machines use 8.3 filename encoding (GETDSFNAME compresses 6-digit WOs via A-J prefix), but that's irrelevant to the server-side pipeline.

**Why:** DOS 8.3 filenames are lossy encodings of the real SN. The old DFWDS.exe existed solely to reverse this encoding. By reading the SN from the data, we eliminate the rename step entirely and decouple the pipeline from DOS filesystem limitations.

**How to apply:** Any new import/export code should use `serial_number` from the parsed record, never derive SNs from filenames. This applies to all product families including future ones.