1. Exit location: where the infantry will appear.
2. Rally point: where the infantry is moving to from the exit location. Even if the building is given a new rally point, the infantry will still first move to this hardcoded location, before going to the assigned rally point.
Using the key ExitCoord, the game only allows to specify the first location, where an infantry appears after being built.
Using GDIBarracks=yes or NODBarracks=yes on a Factory=InfantryType changes the default exit location and the default rally point.
These locations also depend on the foundation size and change between different foundations.

ExitCoord has 3 values X,Y,Z.
X defines offset along the \ cell grid axis (positive value going SE, negative value going NW)
Y defines offset along the / cell grid axis (positive value going SW, negative value going NE)
Z seems to have no functionality (maybe already an error by WW and it actually accepts only X and Y )
The location offset is defined in leptons. One cell = 256 leptons.
Attached is an image showing the 2 default locations with ExitCoord=0,0,0 and different foundation sizes.
The cell where the arrow starts is the exit location.
The cell where the arrow ends the hardcoded and unchangeable rally point.
Yellow for GDIBarracks=yes
Red for NODBarracks=yes