^----------^----------^ REGIONAL
     __        __        __OFFICES
1 <----> 1 <----> 1
     ---        ---        ---
                              OTHERS\/
-^-------^-------^------^---------^
__     __     __    ___      __
2     3     4    4P      5
---     ---     ---    -^^-      ---

 ^----^       ^----^
__  __    ___  __
3  4    4X  5   ^-----^
---  -^-    ----  ---  ___  __
      ^                4X  5
    ___               ----  ---
    5R -------------^
    -^^-      /-----------------\
     __      __     __      ___
     R      4     5      5R
     ---      ---     ---      ----