Math Behind Fusion of FIXED POSE (AprilTag Pose)

[zauberflote1]

Hello,
I am curious about the math behind the "fusion" of the fixed pose coming from the apriltags. From what I understood reading pose_filter.c and geometry.c, the filter uses a ring buffer and finds the average of the values buffered as the new correct values of x, y, z, and yaw. Could anyone confirm this?