By example, if you select the menu 2D Camera, and create a new camera,
the name of this new camera will appear in the Message Box
of the Script Dialog. Later, you will invoque this object
with that name.
If any 2D Scene still doesn't exist, it will
create a new 2D Scene and the camera created
will be looking at the new 2D Scene.
If you want to explicitely specify the 2D Scene, you will have to use appropriate TCL commands.
A way to do this could be to enter the following commands in the Command Box of the Script Dialog:
new scn2D
scn2D1
new cam2D -scene scn2D1
cam2D1
When you want to know which scn2D a cam2D is watching, use the TCL function:
cam2D1 -scene
scn2D1
It returns the name of the 2D Scene.