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

# SeSegment

`SeSegment` models the X12 SE transaction-set trailer, the closing segment that pairs with an `StSegment` header to bound a single transaction set. Its control number is zero-padded to at least four digits on output, matching the format used by the paired `StSegment.ControlNumber` ([BR-041](../../business-rules.md#br-041-st-and-se-control-numbers-zero-padded-to-four-digits)).

## Purpose
- Represents the SE segment identity via `SegmentId` returning the literal `"SE"` ([BR-020](../../business-rules.md#br-020-first-element-is-the-segment-identifier)).
- Carries `NumberOfSegments`, the count of segments included in the transaction set being closed.
- Carries `ControlNumber`, zero-padded to at least four digits on `Build()` to match the paired `StSegment.ControlNumber` format ([BR-041](../../business-rules.md#br-041-st-and-se-control-numbers-zero-padded-to-four-digits)).

## 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 X12 segment identifier `"SE"`. |
| NumberOfSegments | `int NumberOfSegments { get; set; }` | The number of segments included in the transaction set, counting ST through SE inclusive (SE01), element 1. |
| ControlNumber | `long ControlNumber { get; set; }` | The transaction set control number matching the paired `StSegment.ControlNumber` (SE02), zero-padded to at least four digits on `Build()` ([BR-041](../../business-rules.md#br-041-st-and-se-control-numbers-zero-padded-to-four-digits)). |
| Build | `IEdiSegment Build()` | Creates a `SegmentBuilder("SE")`, adds `NumberOfSegments` at element 1, and adds `ControlNumber` formatted with at least four digits (using the greater of its natural digit count or four) at element 2, returning the built segment ([BR-041](../../business-rules.md#br-041-st-and-se-control-numbers-zero-padded-to-four-digits)). |
| Fill | `void Fill(IEdiSegment segment)` | Reads elements 1-2 via `GetChildValue`, converting to `int`/`long`, into `NumberOfSegments` and `ControlNumber`. |
| Parse | `static SeSegment Parse(IEdiSegment segment)` | Instantiates a new `SeSegment`, calls `Fill(segment)` on it, and returns it. |

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