# Table of contents:

• Introduction
• Client/Request
• Server/Response
• Examples
  • As a response to MSG A
  • As a response to MSG D
  • Invalid context
• Known changes

# Introduction

ACK is a command introduced with MSNP2.

It is a Switchboard Server command, without a response payload.

Used as a positive response to MSG A, and later MSG D commands.

# Client/Request

This command can not be sent from the client.

# Server/Response

ACK TrID

# Examples

# As a response to MSG A

C: MSG 1 A 68
MIME-Version: 1.0
Content-Type: text/plain;charset=UTF-8

message
S: ACK 1

# As a response to MSG D

Since MSNP9.

C: MSG 2 D 73
MIME-Version: 1.0
Content-Type: application/octet-stream

data message
S: ACK 2

# Invalid context

Inherited from being an unimplemented command.

C: ACK 3

Server disconnects client.

# Known changes

• MSNP9: Now happens as a response to MSG D.