Why does ArduPilot still use the deprecated MAVLink frame MAV_FRAME_BODY_OFFSET_NED instead of MAV_FRAME_BODY_FRD?

According to the official MAVLink documentation,
MAV_FRAME_BODY_OFFSET_NED has been deprecated since August 2019 and replaced by MAV_FRAME_BODY_FRD.

Source:
https://mavlink.io/en/messages/common.html#MAV_FRAME

The MAVLink spec states:

  • “MAV_FRAME_BODY_OFFSET_NED is the same as MAV_FRAME_BODY_FRD”

  • “DEPRECATED: Replaced by MAV_FRAME_BODY_FRD (2019-08)”

However, in ArduPilot’s current implementation and documentation,
MAV_FRAME_BODY_OFFSET_NED is still used as one of the valid coordinate frames for commands such as SET_POSITION_TARGET_LOCAL_NED.

ArduPilot docs:
https://ardupilot.org/dev/docs/copter-commands-in-guided-mode.html#set-position-target-local-ned


My question:

Is this simply because ArduPilot has not yet updated to the newer MAVLink frame definitions,
or is there a specific reason why MAV_FRAME_BODY_OFFSET_NED continues to be supported instead of MAV_FRAME_BODY_FRD?

If ArduPilot uses a custom or older MAVLink dialect, is there a plan to migrate to MAV_FRAME_BODY_FRD in the future?