Default transform direction if tf2?

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I'm instantiating a tf2::Quaternion from a custom quaternion (scalar first) defined as the rotation of a vector from inertial to body coordinate system. In the next step I'm instantiating a tf2::Matrix3x3 from said tf2::Quaternion. The DCM I obtain seems to have the opposite coordinate transform direction i.e. going from body to inertial. Is this transform direction default in tf2?

I have tracked down the 'setRotation(const Quaternion& q)' function in Matrix3x3.h that is used in the tf2::Matrix3x3 constructor taking a tf2::Quaternion as an argument. But I'm not sure how to deduce the coordinate transform direction. Perhaps someone can shed some light on this - or just point out if have gotten everything backwards.

I'm on ROS2 Foxy if that matters.

Thanks!