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How to Use the Blend-Point Editor
see also: Blend-Point: Y-Value Control Buttons, Blend-Point: Y-Value Radio Buttons,Blend-Point Editor: Data Fields
see also: How to Think about Segments and Blend-Points
The Blend-Point Editor is used to edit the blend-points.
We will use the default motion as a starting point. So, use Add Motion to add a new default motion.
We will then use the Blend-Point Editor to change the blend-point motion conditions.
The default motion also has all the segments set as the most flexible segment type - the Flexible Polynomial.
Use you mouse to click on the second segment (the horizontal one in the top (position) graph).
The segment will turn red once you have selected it.
The Blend-Point that is edited will be the left one of the selected segment, at the start of the red segment.
First. - the X-Values
Edit the X-Value of the blend-point - use your mouse to click on the left and right spin box in the X-Value 
. Keep an eye on the blend-point in the graphs.
You will see the blend-point slide left or right across the motion, from an initial value of 90 degrees, without changing the overall length of the motion design.
You cannot change the value beyond the blend-points either side of the blend-point being edited.
Note that the default units for the X Value are degrees.
Next : Y-Values - Position Changes
Use the Pos(ition) Value Spin-Box.
In the position graph (the top graph) you will notice the blend-point you are editing moves vertically to match the value you have changed the position to in the Position Data Field.
Both segments (the selected and the segment before the selected segment) automatically update to suit the new Position condition.
Notice that the default units for Position are mm (millimetres)
You will also notice in the velocity and acceleration graphs of the selected segment that the segment data updates to satisfy the new position boundary condition .
Next : Y-Values - Velocity Changes
use the Vel(ocity) Value Spin-Box to edit the Velocity of the Blend-Point.
Keeping an eye on the blend-point in the graphs , you will see the slope or gradient of the Position graph at the blend-point changes automatically (without changing the actual position at the Blend-Point) as you change the velocity.
Also, if you look at the velocity graph (the second one down), you will notice the blend-point move vertically as you make changes to the Velocity value with the spin-box.
The blend-point will not move in the acceleration.
In addition to the change to the actual blend-point, the segments data either side of the blend-point being edited will change to suit the new condition.
Next : Y-Values - Acceleration Changes
Use the Acc(eration) Value Spin-Box to edit the Acceleration at the Blend-point.
Again keeping your eye on the blend-point in the graphs, you will see the slope of the Velocity Graph at the blend-point changes automatically (without changing the velocity value at the blend-point itself) as you make changes to the Acceleration value of the blend-point.
The acceleration value will obviously change at the blend-point to suit the value you spin too.
Next : Y-Values - Jerk Changes
You can also do the same sort of editing to the Jerk condition. If you want to see what's going on with the jerk, then you can switch the jerk graph on using View | Show Jerk, or clicking on the 
icon in the View Menu.
Once you have good understanding of how the values can be edited and understand the effects on the motions as you change them, it would be a good idea to play around with the Blend-Point Control Buttons.
Understanding these is critical to getting the most out of MotionDesigner.
You will notice that many of the Segment Types do not have available all of the Blend-Point options available in the Blend-Point Editor. This is because the Segment is fully described by the equations, and they not flexible enough to specify the motion derivatives directly, other than the initial and final position.