Precise assy option question

Question is about the setting:

In the Customer defaults, Teamcenter Integration, Assembly

"save imprecise assemblies as precise on save precise assembly"

The "tip" simply says "This option determines whether or not imprecise assemblies will be saved as precise on save precise assembly"

Does that simply mean unchecking will disable the ability to save a precise assembly in NX?

or

Will it disable sub-assemblies from becoming precise, when you save an upper level assembly as precise?

I ask, because we have some assemblies we want precise, but have found some subassemblies that we need imprecise, have been turned precise.  I'm sure it was user error, having something in the assembly structure that should have been removed before going precise.  I'm just looking to eliminate human error.

Thanks!