Players see the action of the game through a camera that sits at certain position, direction and focal length. The camera can be first person where the player sees the action from the position of their character or they can look from behind the character in third person perspective such as in the picture below:

The camera focal length can be changed by setting the camera 'focallength' attribute. Likewise with the depth of view.

The above diagram explains the camera parameters related to third person perspective. 'cameraheightoffset' specifies the height of the camera above the ground. In third person mode the camera cannot below this height above the ground.
Other camera attributes are related to third person perspective such as the default distance at the which a player starts in third person mode ('thirdpersondist'). The is also the 'thirdpersonheight' which specifies how height off the ground the camera is behind the actor when in third person mode. There is also 'thirdpersonmaxdist' which is the maximum distance the camera can go behind the players character.