Creates a new map marker at the given position. The marker will be created for every connected player as well as all JIP players. The marker name has to be unique; the command will be ignored if a marker with the given name already exists.
Important
The marker will be visible only once at least markerType has been defined:
If the marker position is given in 3D format, the z-coordinate is stored with the marker and will be used when the marker is passed to commands such as createVehicle, createUnit, createAgent, createMine or setVehiclePosition.
When a marker is manually placed in the editor, z is always 0, which means the marker is placed on the ground. But when the player places a marker on the map in game, it is placed at sea level, so the z-coordinate of that marker is -getTerrainHeightASL markerPos "userMarker";.
Multiplayer optimisation: Global marker commands always broadcast the entire marker state over the network.
As such, the number of network messages exchanged when creating or editing a marker can be reduced by performing all but the last operation using local marker commands, then using a global marker command for the last change (and subsequent global broadcast of all changes applied to the marker).
When creating a marker with the name format: "_USER_DEFINED #n1/n2/n3".
n1 can be used to set the owner, n2 I think is an incrementing index to ensure markers are unique, to this end also mangle some more characters onto the end of the string, and n3 is the channel ID the marker is in.
If you use the letter "/" in the name, it may break the channel visibilities (especially in MP).
Possible reason is described above by Tirpitz, the engine may confuse which channel the marker belongs to after the "/".
Leopard20
You can use a helper function if you intend to call createMarker with duplicate marker names. It doesn't necessarily guarantee that the marker has been created (e.g. it could fail not due to duplicate name, but due to maximum number of allowed markers reached)