# Table of contents:

# Introduction

SYN is a command introduced with MSNP2

It is a Notification Server command, without a request or response payload.

Synchronizes user options and every contact list.

This command can only be sent once. Any further uses of this command in the same session is Undefined Behaviour.

# Client/Request

SYN TrID list-version {settings-version}

Where list-version is the last saved List Version this client remembers. If the client doesn't remember any information, this is 0. With MSNP10 and ABCHMigrated: 1, this is changed from a numerical value to a timestamp.

Where settings-version is the last saved Settings Version this client remembers. If the client doesn't remember any settings, this is set to 0. Added since MSNP10. With ABCHMigrated: 1, this is changed from a numerical value to a timestamp.

# Server/Response

SYN TrID list-version {settings-version} {amount-of-users} {amount-of-groups}

Where list-version is either the current or new List Version, depending if the client's version of this parameter is the same as the one the server has. With MSNP10 and ABCHMigrated: 1, this is changed from a numerical value to a timestamp.

Where settings-version is either the current or new Settings Version, depending if the client's version of this parameter is the same as the one the server has. Added since MSNP10. With ABCHMigrated: 1, this is changed from a numerical value to a timetstamp.

Where amount-of-users is the amount of unique LST responses your client is going to have to expect. Added since MSNP8.

Where amount-of-groups is the amount of LSG responses your client is going to have to expect. Adec since MSNP8.

# Examples

# First generation

Only in MSNP2 to MSNP4.

Used commands: 

C: SYN 1 0
S: SYN 1 255
S: GTC 1 255 A
S: BLP 1 255 AL
S: LST 1 FL 255 1 1 anotheruser@hotmail.com another%20user
S: LST 1 AL 255 1 1 anotheruser@hotmail.com another%20user
S: LST 1 BL 255 0 0
S: LST 1 RL 255 1 1 anotheruser@hotmail.com another%20user

# Second generation

Only in MSNP5 and MSNP6.

Used commands: 

C: SYN 2 0
S: SYN 2 255
S: GTC 2 255 A
S: BLP 2 255 AL
S: PRP 2 255 PHH 123%20(4567)
S: PRP 2 255 PHW
S: PRP 2 255 PHM
S: PRP 2 255 MOB N
S: PRP 2 255 MBE N
S: LST 2 FL 255 1 1 anotheruser@hotmail.com another%20user
S: BPR 255 anotheruser@hotmail.com PHH 1%20(222)%20333%204444
S: BPR 255 anotheruser@hotmail.com PHW
S: BPR 255 anotheruser@hotmail.com PHM
S: BPR 255 anotheruser@hotmail.com MOB N
S: LST 2 AL 255 1 1 anotheruser@hotmail.com another%20user
S: LST 2 BL 255 0 0
S: LST 2 RL 255 1 1 anotheruser@hotmail.com another%20user

# Third generation

Only in MSNP7.

Used commands: 

C: SYN 3 0
S: SYN 3 255
S: GTC 3 255 A
S: BLP 3 255 AL
S: PRP 3 255 PHH 123%20(4567)
S: PRP 3 255 PHW
S: PRP 3 255 PHM
S: PRP 3 255 MOB N
S: PRP 3 255 MBE N
S: LSG 3 255 1 2 0 Other%20Contacts 0
S: LSG 3 255 2 2 1 Friends 0
S: LST 3 FL 255 1 1 anotheruser@hotmail.com another%20user 0
S: BPR 255 anotheruser@hotmail.com PHH 1%20(222)%20333%204444
S: BPR 255 anotheruser@hotmail.com PHW
S: BPR 255 anotheruser@hotmail.com PHM
S: BPR 255 anotheruser@hotmail.com MOB N
S: LST 3 AL 255 1 1 anotheruser@hotmail.com another%20user
S: LST 3 BL 255 0 0
S: LST 3 RL 255 1 1 anotheruser@hotmail.com another%20user

# No groups specified

This only happens if the only group is ~, and you set the client to sort by groups.

Used commands: 

S: LSG 3 255 1 1 0 ~ 0

... 

C: REG 4 0 Other%20Contacts 0
S: REG 4 256 0 Other%20Contacts 0
C: ADG 5 Coworkers 0
C: ADG 6 Friends 0
C: ADG 7 Family 0
S: ADG 5 257 1 Coworkers 0
S: ADG 6 258 2 Friends 0
S: ADG 7 259 3 Family 0

# Fourth generation

Only in MSNP8 and MSNP9.

Used commands: 

C: SYN 8 0
S: SYN 8 255 1 2
S: GTC A
S: BLP AL
S: PRP PHH 123%20(4567)
S: LSG 0 Other%20Contacts 0
S: LSG 1 Friends 0
S: LST anotheruser@hotmail.com another%20user 11 0
S: BPR PHH 1%20(222)%20333%204444

# No groups specified

This only happens if the only group is ~, and you set the client to sort by groups.

Used commands: 

S: LSG 0 ~ 0

... 

C: REG 9 0 Other%20Contacts 0
S: REG 9 256 0 Other%20Contacts 0
C: ADG 10 Coworkers 0
C: ADG 11 Friends 0
C: ADG 12 Family 0
S: ADG 10 257 1 Coworkers 0
S: ADG 11 258 2 Friends 0
S: ADG 12 259 3 Family 0

# Fifth generation

Only in MSNP10 and MSNP11.

Used commands:

# Without GUIDs

Only with ABCHMigrated: 0. 

C: SYN 13 0 0
S: SYN 13 255 255 1 2
S: GTC A
S: BLP AL
S: PRP MFN example%20user
S: PRP PHH 123%20(4567)
S: LSG Other%20Contacts 0
S: LSG Friends 1
S: LST N=anotheruser@hotmail.com F=another%20user C=anotheruser@hotmail.com 11 0
S: BPR PHH 1%20(222)%20333%204444

# With GUIDs

Only with ABCHMigrated: 1. 

C: SYN 14 0 0
S: SYN 14 2024-10-23T14:02:48.5360000-07:00 2024-10-23T14:02:48.5360000-07:00 1 2
S: GTC A
S: BLP AL
S: PRP MFN example%20user
S: PRP PHH 123%20(4567)
S: LSG Other%20Contacts d6deeacd-7849-4de4-93c5-d130915d0042
S: LSG Friends f60efbe7-94af-4b16-b926-e4e10878d32
S: LST N=anotheruser@hotmail.com F=another%20user C=c1f9a363-4ee9-4a33-a434-b056a4c55b98 11 d6deeacd-7849-4de4-93c5-d130915d0042
S: BPR PHH 1%20(222)%20333%204444

# Sixth generation

Only in MSNP12. 

C: SYN 15 0 0
S: SYN 15 2024-10-23T14:06:20.5360000-07:00 2024-10-23T14:02:48.5360000-07:00 1 2
S: GTC A
S: BLP AL
S: PRP MFN example%20user
S: PRP PHH 123%20(4567)
S: LSG Other%20Contacts d6deeacd-7849-4de4-93c5-d130915d0042
S: LSG Friends f60efbe7-94af-4b16-b926-e4e10878d32
S: LST N=anotheruser@hotmail.com F=another%20user C=c1f9a363-4ee9-4a33-a434-b056a4c55b98 11 1 d6deeacd-7849-4de4-93c5-d130915d0042
S: BPR PHH 1%20(222)%20333%204444

# Removed

Since MSNP13. 

C: SYN 16 0 0

Server disconnects client.

# Known changes