Mavlink commands not supported by PX4

Hey I am new with MavLink and PX4.
We currently develop a solution with Pix Hawk 2.1 and RasbPI.
I need to use some MavLink Commands but not all are supported by PX4.
For example I managed to use MavLink 206 to set the camera but I was not able to use 186 altitude change command.
I understood that not all commands are supported by PX4

Could you help me with some documentation link about which MavLink are supported by PX4 and which not.

Thank you