On the Cam Lao Nam terrain, place a minimum of two Terrain Tunnel Entrance modules, and you shall find that both modules link to the same section of tunnel—this is not ideal, given that each tunnel has multiple ladder sections that may act as an exit.

Given that each variant of the Tunnel 01 section contains a ladder, and on this map each tunnel variant contains four (4) of these, it may therefore be ideal to let the user define in the module to which ladder they wish that specifick module to link to.
 As there is a possibility of having one (1) to any number of ladder sections should the user define a custom tunnel system, it may be more extensible to link the module to the section of tunnel to which it ought to lead—this would allow the module to function on other terrains as well, should the user place a tunnel section and module on the map and synch them together.