To Constrain the Pending Data Point to a Drawing Plane Axis
- Position the pointer near the desired axis. When the pointer is on an axis, a highlighted line is displayed from the drawing plane origin to the pointer location.
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Press the Enter key.
Smart Lock is engaged. Its effect is to constrain the pending data point to the axis.

Figure 1. Constraining the pending data point along x-axis. 

Figure 2. Constraining the pending data point along y-axis. 
You now can constrain the pending data point to a precise distance along the axis by keying in a value, or simply by snapping a tentative point to an element or monument point and accepting the tentative point as the data point location.
Tip: To disengage Smart Lock and unconstrain the pending data point, press Enter again. The Enter key turns off Smart Lock.Note: Smart Lock will not lock to an axis when you are entering coordinate values into its field. Instead, AccuDraw returns the dynamic element to free motion.