Hello guys

I am trying to figure out if the actual catproduct has a axis system or if the axis system in a catproduct goes off of the first part in the assembly.
I work in the aircraft industry and we have issues with going from one system to another and depending on what catproduct we bring in some laser data, it seems to be off a bit in one assembly and not the other. we try and always use what they call aircraft cordinates

can anyone explain the axis system in catia to me a little better