# Introduction
`SYN` is a command introduced with [MSNP2](../versions/msnp2.md)

# 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](../versions/msnp10.md) 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](../versions/msnp10.md).
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](../versions/msnp10.md) 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](../versions/msnp10.md).
With `ABCHMigrated: 1`, this is changed from a numerical value to a timetstamp.

Where `amount-of-users` is the amount of unique [LST](lst.md) responses
your client is going to have to expect. Added since [MSNP8](../versions/msnp8.md).

Where `amount-of-groups` is the amount of [LSG](lsg.md) responses
your client is going to have to expect. Adec since [MSNP8](../versions/msnp8.md).

# Examples

## First generation
*Only in [MSNP2](../versions/msnp2.md) to [MSNP4](../versions/msnp4.md).*

Used commands:
* [GTC](gtc.md)
* [BLP](blp.md)
* [LST](lst.md)

```
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](../versions/msnp5.md) and [MSNP6](../versions/msnp6.md).*

Used commands:
* [GTC](gtc.md)
* [BLP](blp.md)
* [PRP](prp.md)
* [LST](lst.md)
* [BPR](bpr.md)

```
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](../versions/msnp7.md).*

Used commands:
* [GTC](gtc.md)
* [BLP](blp.md)
* [PRP](prp.md)
* [LSG](lsg.md)
* [LST](lst.md)
* [BPR](bpr.md)

```
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.*

```
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](../versions/msnp8.md) and [MSNP9](../versions/msnp9.md).*

Used commands:
* [GTC](gtc.md)
* [BLP](blp.md)
* [PRP](prp.md)
* [LSG](lsg.md)
* [LST](lst.md)
* [BPR](bpr.md)

```
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.*

```
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](../versions/msnp10.md) and [MSNP11](../versions/msnp11.md).*

Used commands:
* [GTC](gtc.md)
* [BLP](blp.md)
* [PRP](prp.md)
* [LSG](lsg.md)
* [LST](lst.md)
* [BPR](bpr.md)

### 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](../versions/msnp12.md).*
```
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](../versions/msnp13.md).*
```
C: SYN 16 0 0
```

Server disconnects client.

# Known changes
* [MSNP5](../versions/msnp5.md): Added [PRP](prp.md) and [BPR](bpr.md) support.
* [MSNP7](../versions/msnp7.md): Added [LSG](lsg.md) and groups support in [LST](lst.md).
* [MSNP8](../versions/msnp8.md): Unset properties are omitted,
  added new response parameters to replace [LSG](lsg.md) and [LST](lst.md) iterator parameters.
  Transaction IDs and List Versions were removed from used commands.
* [MSNP10](../versions/msnp10.md): Added new parameters for the current settings version.
  With `ABCHMigrated: 1`, the List Version and Settings Version are changed to ISO 8601 timestamps.
* [MSNP12](../versions/msnp12.md): [LST](lst.md): Added support for Network IDs.
* [MSNP13](../versions/msnp13.md): Removed (automatic disconnection).
  Use the [Address Book Service](../services/abservice.md)
  and the [Contact Sharing Service](../services/sharingservice.md) instead.