Briefly, holes bored into the earth for exploration,
mining, engineering, scientific, fluid extractive or fluid transportive
purposes need to be defined/located in 3 dimensional earth space. The
beginning (collar) of the hole can be located (surveyed) by traditional
surveys or GPS without problems.
Beyond the collar lies the path of the earthbound
borehole that is never naturally straight without some type of human
intervention or control, and that path is not available for direct
observation.
So, a valid question about a borehole is "Where did it go?"
Or if the drilling had produced samples of a particular rock traversed
in the borehole, the question might be "Where exactly was this
sample rock located in the earth?" Yes, the path of the borehole
can deviate sufficiently to make answers to these questions critically
important.