# Introduction

This Programmers Guide describes the following features of the Barcode application:

* Provides descriptions of the message packets.
* Provides Barcode commands and examples.

This manual contains explicit information regarding use of these barcode commands and their responses to the host.

### Intended Audience

This document is intended for the integrators as a reference guide that provides technical information.

### Knowledge Prerequisites

It is assumed that the user of this guide is familiar with these concepts:

* CAM application
* Application Programming Interface (API) to the Verifone programmable PINPads
* Different payment devices and VeriFone terminals

### Definition of Terms

This table lists the terms and abbreviations that are used throughout this document:

| Term | Description               |
| ---- | ------------------------- |
| CXPI | Combined XPI              |
| LSB  | least-significant bit     |
| MSB  | most-significant bit      |
| msec | millisecond               |
| V/OS | Verifone Operating System |


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