typedef struct MPITrajectory {
    double    velocity;
    double    acceleration;
    double    deceleration;
    double    jerkPercent;
    double    accelerationJerk;
    double    decelerationJerk;
} MPITrajectory;

The Trajectory structure is within the MPIMotionVelocity structure which in turn is within the MPIMotionParams structure. The data contained in MPITrajectory are the parameters used in certain motion profiles.