When using the Marlin LCD menu, there is an option under Control -> Motion -> Z Offset that set's a Z Offset to be applied after G28. I'm using Marlin "stable" version 1.0.2-1 on a Sanguinololu 1.3+ Prusa i3 style printer.

My questions are:

1) Why is the default .5 mm and it can't be removed?
2) Is there any way to access the value in this setting via G or M codes in a terminal?

Thanks.

- Alex O.