tool change

I have a technical question; using CNC what is the best way to
execute a tool change?

In CNC programs the 1st tool is very easy because you can adjust the
tool to the part then move to 0,0,0. A 2nd tool change is different
because the new tool may be longer, shorter, etc. Additionally you
would not want to change Z (or any other axis) in the process of the
tool change (or certainly you would want the axis to read the same
before and after)

Thanks,
Ken