I've never understood why you would call-out the position of a hole that is located on the datum referenced in the FCF. Would someone please explain this to me, particularly, what are they trying to determine? Thanks.
The holes need to be in the correct position to each other so the mating part can assemble.
The position of the mating part however doesn't need to be controlled so tightly - two common scenarios I've seen for this are:
1) For affixing a label or engraved plate,
2) for mounting components in electronics or fluid applications, where there's a flexible connection (tube or wire) going to the mating part so it doesn't need to be precisely located
