Quote from "Skulltag Version History.txt"
Added new DECORATE actor flag SERVERSIDEONLY. The clients don't spawn such actors, only the server does. Therefore, spawning or manipulating these actors does not need network bandwidth. Only use it on actors that are always invisible and don't block the movement of players. [Torr Samaho]

Quote from Torr Samaho
Yes, it's not allowed to use SERVERSIDEONLY like this.

Actor DummyPlayer 32767
{
    Health 2147483647
    Radius 16
    Height 56
    Mass 100
    +SOLID
    +SHOOTABLE
    +DROPOFF
    +SLIDESONWALLS
    +CANPASS
    +FLOORCLIP
    +WINDTHRUST
    +TELESTOMP
    +NOBLOCKMONST
    States
    {
    Spawn:
        TNT1 A 0
        TNT1 A 0 A_SpawnItemEx ("ServerSideActor", 0, 0, 0, 0, 0, 0, 0, 0, 0)
        TNT1 A 0 A_SpawnItemEx ("ClientSideActor", 0, 0, 0, 0, 0, 0, 0, SXF_CLIENTSIDE, 0)
        TNT1 A 1
        Loop
    }
}

Actor ServerSideActor
{
    +NOBLOCKMAP
    +NOGRAVITY
    States
    {
    Spawn:
        PLAY A 2 Bright
        Stop
    }
}

Actor ClientSideActor
{
    Translation 2
    +NOBLOCKMAP
    +NOGRAVITY
    States
    {
    Spawn:
        PLAY A 2 Bright
        Stop
    }
}

Quote from unknownna
The actor is spawned on the client-end, but once you desync the client-side and server-side positions, the view bob issue will occur if you bump into the server-side actor.

Quote from Torr Samaho
Ah, so when you say "server-side" you mean an actor that is spawned by the server on the server and on the clients (which actually just is a normal actor to me, as all actors without CLIENTSIDEONLY or SERVERSIDEONLY should be there on clients and server).

Quote from Torr Samaho
So the bug here is not the view bobbing, this is just a symptom of the actual bug, i.e. the desync of the actor position on clients and server.

Quote from Torr Samaho
Since ClientSideActor is client side, all restrictions for CLIENTSIDEONLY actors apply. For instance, it may not be solid.