---
title: DmgSegment
summary: API reference for DmgSegment.
status: draft
owner: SAIF Doc Gen
last_reviewed: 2026-09-15
library: SAIF.Framework.Common.Files
reference_type: package
---

# DmgSegment

`DmgSegment` models the X12 DMG demographic information segment, used in 837 claim transactions to carry a patient's or subscriber's date-of-birth and gender. It is an inbound-only segment in this library: `Build()` throws `NotImplementedException` because outbound DMG generation is not supported ([BR-054](../../business-rules.md#br-054-dmg-hi-sv1-sv2-sv3-are-inbound-only-segments)).

## Purpose
- Represents the DMG segment identity via `SegmentId`, though notably returning the mixed-case literal `"Dmg"` rather than the X12 identifier `"DMG"` ([BR-020](../../business-rules.md#br-020-first-element-is-the-segment-identifier)).
- Carries `Format` (the date-format qualifier), `BirthDate`, and `GenderCode` describing the individual's demographic data.
- Is inbound-only: `Fill(IEdiSegment)` populates the object from a parsed segment, but `Build()` throws `NotImplementedException` ([BR-054](../../business-rules.md#br-054-dmg-hi-sv1-sv2-sv3-are-inbound-only-segments)).

## Context
- Namespace: `SAIF.Common.Files.Edi.Segments`
- Assembly/package: `SAIF.Framework.Common.Files`

## Public members
| Member | Signature | Purpose |
| --- | --- | --- |
| SegmentId | `string SegmentId { get; }` | Returns the literal `"Dmg"` (mixed case, not the X12 identifier `"DMG"`). |
| Format | `string Format { get; set; }` | The date-format qualifier for `BirthDate` (DMG01), read at element 1. |
| BirthDate | `DateTime BirthDate { get; set; }` | The individual's date of birth (DMG02), parsed via `DateMaker.MakeDateTime` at element 2. |
| GenderCode | `string GenderCode { get; set; }` | The individual's gender code (DMG03), read at element 3. |
| Build | `IEdiSegment Build()` | Always throws `NotImplementedException`; outbound DMG generation is not supported ([BR-054](../../business-rules.md#br-054-dmg-hi-sv1-sv2-sv3-are-inbound-only-segments)). |
| Fill | `void Fill(IEdiSegment segment)` | Reads elements 1-3 via `GetChildValue`, parsing `BirthDate` via `DateMaker.MakeDateTime`, into `Format`, `BirthDate`, and `GenderCode`. |
| Parse | `static DmgSegment Parse(IEdiSegment segment)` | Instantiates a new `DmgSegment`, calls `Fill(segment)` on it, and returns it. |

## Behavioral notes
- `SegmentId` returns the literal `"Dmg"` rather than the uppercase X12 identifier `"DMG"` that every other segment class in this library uses; whether this is intentional or a defect that would break any case-sensitive id-based segment lookup is unconfirmed**.

## Constraints and usage notes
- Any caller invoking `Build()` on a `DmgSegment` receives a `NotImplementedException` rather than a built segment ([BR-054](../../business-rules.md#br-054-dmg-hi-sv1-sv2-sv3-are-inbound-only-segments)).

> **Note:** Statements marked with `**` could not be confirmed; treat
> as unknown until verified.

## Sources
- Common\SAIF.Common.Files\Edi\Segments\DmgSegment.cs