by Alberto Torres Ruiz (dithi) --- quoting the patch submission This patchs adds the properties IpoCurve.driverBone and IpoCurve.driverBone2 and modifies IpoCurve.driverChannel to allow OB_ROT_DIFF. It sets the driver type to pose if IpoCurve.driverBone is not empty or None. Otherwise the driver type is set to object. Attached is the patch (with python doc) and an example .blend. It also fixes the confusing description of IpoCurve.driver