(Sometimes you feel like a nut, sometimes you don't.)
The OSNAPZ command in AutoCAD reminds me of those commercials.
(Sometimes I want elevation, sometimes I don't.)
The OSNAPZ command is an easy way to switch between snapping to an elevation and forcing an elevation when creating or editing AutoCAD objects. When drafting in both the Civil Engineering and Land Surveying fields, both options are useful.
From the AutoCAD help documentation:
With OSNAPZ set to 0, OSNAP uses the Z-value of the specified point. For a polyline, the elevation selected for the first vertex will be assigned as the elevation of the polyline.
With OSNAPZ set to 1, OSNAP substitutes the Z-value of the specified point with the elevation (ELEV) set for the current UCS. With the system variable ELEV set to 0, the elevation will default to 0 for all selected points.
Now hopefully I can finally get that song out of my head.