ISO - Flatness CZ of Offset Features

[Mech1595]

Hello All,

I received a customer print for review with the following callout for [Flatness | 0.1 CZ] for the two identified surfaces. I created an example with a simplified model below, but kept all of the notes/callouts/etc. the same as the customer print.

My experience is limited with ISO GPS, but I understand the concept of CZ when applied to co-planar surfaces (as shown in the second image). I'm just a little confused on what the tolerance zone will look like in this example, with the two offset surfaces. Is this still just a form control? Do I treat it as two separate (but parallel) tolerance zones, and ignore the basic offset?

Second image pulled from ISO 1101 for reference

 

[Woosang]

Per ISO 5458:2018, flatness and strainghtness can define a pattern and control not only the orientation but also the location of features in a group, but in condition that the features are coaxial or coplanar. So in OP's case flatness should not be used since the surfaces are not coplanar. Please refer to the screenshot from ISO 5458.