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

# SvSegmentBase

`SvSegmentBase` is the shared abstract base class for the three X12 service-line segments — `Sv1Segment` (professional/SV1), `Sv2Segment` (institutional/SV2), and `Sv3Segment` (dental/SV3). It owns the composite procedure-code element (qualifier, service code, up to four modifiers, and description) that is structurally identical across all three service-line segment types, so each subclass builds and fills that shared composite through `BuildElement()`/`FillServiceCode(IEdiCompositeDataElement)` instead of duplicating the composite-mapping logic.

## Purpose
- Models the procedure/service-code composite element (qualifier + code + up to four modifiers + description) common to SV1, SV2, and SV3 segments.
- Provides `BuildElement()` so subclasses can construct the outbound composite element from `Qualifier`/`ServiceCode`/modifier properties.
- Provides `FillServiceCode(IEdiCompositeDataElement)` so subclasses can populate those same properties from an inbound composite element.

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

## Public members
| Member | Signature | Purpose |
| --- | --- | --- |
| Qualifier | `string Qualifier { get; set; }` | The procedure-code qualifier identifying the coding system in use (e.g. HCPCS/CPT), read from/written to composite sub-element 1. |
| ServiceCode | `string ServiceCode { get; set; }` | The procedure/service code value itself, composite sub-element 2. |
| ServiceModifierCode1 | `string ServiceModifierCode1 { get; set; }` | The first of up to four procedure modifier codes, composite sub-element 3. |
| ServiceModifierCode2 | `string ServiceModifierCode2 { get; set; }` | The second procedure modifier code, composite sub-element 4. |
| ServiceModifierCode3 | `string ServiceModifierCode3 { get; set; }` | The third procedure modifier code, composite sub-element 5. |
| ServiceModifierCode4 | `string ServiceModifierCode4 { get; set; }` | The fourth procedure modifier code, composite sub-element 6. |
| ServiceDescription | `string ServiceDescription { get; set; }` | A free-text description of the procedure, read from composite sub-element 7 on `FillServiceCode`; not written by `BuildElement()`. |
| BuildElement | `EdiCompositeDataElement BuildElement()` | Constructs a new `EdiCompositeDataElement` populated with `Qualifier` and `ServiceCode` at sub-elements 1-2 and the four modifier codes at sub-elements 3-6. |
| FillServiceCode | `void FillServiceCode(IEdiCompositeDataElement element)` | Reads sub-elements 1-7 of the supplied composite element into `Qualifier`, `ServiceCode`, the four modifier codes, and `ServiceDescription`. |

## Behavioral notes
- `BuildElement()` always writes all four modifier sub-elements regardless of whether they are populated, unlike the sibling `CompositeProcedureCodeElement.BuildElement()`, which omits empty modifiers*.

## Constraints and usage notes
- This is an abstract class; it is only usable through `Sv1Segment`, `Sv2Segment`, or `Sv3Segment`, all of which are inbound-only segments whose `Build()` implementations throw `NotImplementedException` ([BR-054](../../business-rules.md#br-054-dmg-hi-sv1-sv2-sv3-are-inbound-only-segments)).

> **Note:** Statements marked with `*` were inferred from code structure, naming
> conventions, or contextual evidence where direct confirmation was not available
> in source artifacts.

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