Knot documentation is here: http://docs.mcneel.com.s3.amazonaws.com/rhino/6/help/en-us/popup_moreinformation/knot.htm
Knot documentation is incomprehensible because it is devoid of drawings. I made simple drawing, shown below, which may be used to define knot. I drew the red curve first. Then I drew the green line between the control points. Finally, I drew the blue line. The blue line is perpendicular to the red curve and the green line. The knot is part of the red curve. It is defined as the intersection of the red curve with the blue line.
Are the knot values the same as their parameter values and parameters reported by EvaluateUVPt command? Is there a curve equivalent of the EvaluateUVPt command? (command which reports curve parameter at a point picked by Rhino user)
Edit points are documented in this file: https://docs.mcneel.com/rhino/6/help/en-us/popup_moreinformation/editpoint.htm
It says: Edit points on a curve are displayed at knot averages… edit points… are not knots themselves.
What are these knot averages? The edit points are located in the same places as the knots.
Accurate modeling documentation file is here: http://docs.mcneel.com.s3.amazonaws.com/rhino/6/help/en-us/user_interface/accurate_modeling.htm
Example with angle and elevator mode
1. Start the Line command and place the first line point.
2. At the End of line… prompt, move the mouse to the location where the line should end, activate elevator (press Ctrl ), and type <30.
3. A line is drawn at 30 degree angle to the construction plane, ending on the elevator line.
This description is incomplete. You cannot type anything while you hold down the Ctrl key. You have to click left mouse button while holding down the Ctrl key, release the Ctrl key, and finally, type <30.