<< Click to Display Table of Contents >> Navigation: MechDesigner Reference & User Interface > FAQs and 'How do I...?' > Part Editor: FAQs and How to...? > Why is the dimension 'negative' in the Dimension dialog'? 
The – sign appears if the coordinate of the dimension is negative.
Generally, do not delete the – sign, but edit the dimension in the normal way.
Lines have an XY coordinatesystem. •The Origin of a Line is at its startPoint •The +Xaxis of a Line is from its startPoint(1) to its endPoint(2) •The +Yaxis of a Line is at +90º from Line. When we add a dimension that is a perpendiculardistance from the Line, the •dimension will be Positive if in +yaxis half of the Line (blue area in the image) •dimension will be Negative if in the yaxis of the Line (green area in the image) In the top image: •Dimensions from the Line(1 to 2) to Points a and b will be positive •Dimensions from the Line to Points c and d will be negative 

The XAXIS and YAXIS of a Part each has its own coordinatesystem. The image to the left shows the CoordinateSystem of the YAXIS The local +xaxis of the YAXIS of a Part is along the YAXIS! Thus, the local +yaxis of the Yaxis of a Part is at +90º from Yaxis Thus a dimension that is a perpendiculardistance from the YAXIS to a Point is in the green area will be negative ... ... and this is in the +X axis direction of the Part! 