Két példát idézek itt. Mint az első példa írja, "home or starting position", de nem azonos a nullázással, ez a második példából derül ki.
www.dancad3d.com/S0302600.HTM
Run DANCAD3D (tm) and draw your tool path. If you are using DANCAM.EXE (tm) to cut the part be sure that your first and last line segments guide the tool around the projections of the work-piece in a safe manner for motions from and to the home position or the tool might bang into something and ruin the part (also watch out for the vice, clamps, and other fixtures!) In DANPLOT.EXE (tm) the tool normally automatically starts and ends in its up position away from the work-piece, but when drawing tool path files for DANCAM.EXE (tm) you need to take into account how high above the work-piece the starting and ending points in the tool path file need to be to keep the tool clear of the work-piece while the tool will be moving from and then back to the home or starting position. The [P]lotterize and [L]ink drawing commands can be helpful in adding the vertical motions between the cutting motions.

www.tri-c.edu/CATALOG/ 0305/docs/courses/manufacturing.htm
Fundamentals of computer application as aid to machining processes. Emphasis on engineering drawing analysis, using trigonometry and other forms of mathematics to determine programming points; ascertaining implied part dimensions; determinations of machining parameters; calculation of speeds; feeds and tool offset; establishment of work zero and tool home positions.