I am using Arc Map 10.4.1.
I am at odds with the terminology of "Geographic" coordinate and inquire for a better understanding. I have heard many interpretations of this term. Such as: a datum is geographic if one is using lat-long coordinates. Which I have always assumed belong to a "round" earth. However, there are graticules associated with a flat map, that I believe, sometimes have lat-long, such as along the edges of a quad map. When viewing graphics set to a coordinate system like Arc Map, I understand that the geographic coordinate is actually flat, but allows 3d data to be added to the map. But with a cad application like AutoCAD, the opposite is true, one cannot add data to a geographic coordinate, but rather, must be in a projected one such as a state plane, to add 3d data. I find the subject somewhat confusing and look to Esri for some explanation of this "Geographic" concept. So I have ot ask, is it possible to have geographic coordinates for a flat map, as well as a 3d datum, and is the term really just another way to refer to a lat-long coordinate format?