Combines X, Y, and Z values from different points to specify a single point
At any prompt for locating a point, you can enter point filters to specify a single coordinate by extracting the X, Y, and Z values of several points. In the following example, the start point for the line has a coordinate constructed from the X value of the midpoint of the first object you select, with the Y and Z values of the midpoint of the second object you select.
Command: line
Specify first point: .x
of mid
of Select an object
of (need YZ) mid
of Select another object
To point: Specify a point