camera component's Field of View

I am currently building a forklift-based cargo transportation environment using Unreal Engine, and I would like to politely ask a question regarding the camera FOV (Field of View) setting.

In my setup, a rear camera is attached to the forklift to capture the rear view, and the captured image is displayed in real time on a monitor by applying the camera output to a Plane using a Material.
As shown in the images below, the system uses a camera and monitor to provide the rear view, so I named it CMS (Camera Monitoring System).

The detailed settings are shown below.

My question is specifically about the FOV setting.

In the SC_CMS_Bwd Projection settings, I can directly set the FOV value. However, I cannot determine whether this value represents a Horizontal FOV or a Vertical FOV.

If anyone knows whether this FOV value is horizontal or vertical, I would greatly appreciate your help.

Additionally, if possible, I would also like to know the reason or basis for your answer, such as:

  • Unreal Engine official documentation

  • Engine behavior or implementation details

  • Calculation methods

  • Tooltip or editor descriptions

Any reliable reference or explanation would be extremely helpful.

As shown in the images below, the system is implemented by applying the camera output to a Material and displaying it in real time on the monitor.

Thank you very much for your time and assistance.