Civil 3D: tangents' influence area of the Alignment

Specifies the boundaries defined for the criteria of zone of influence of the Alignment stations.
When I did, everything became simple and logical, but at first it made me think.
coord Alignment:
X= 0.0000 Y=-100.0000 Z= 0.0000 (0+000)
X= 0.0000 Y= 0.0000 Z= 0.0000
X= 25.0000 Y= 0.0000 Z= 0.0000
X= 25.0000 Y= -72.5064 Z= 0.0000
X= 63.1982 Y=-109.9988 Z= 0.0000
X= -25.5462 Y=-109.9988 Z= 0.0000
X= -25.5462 Y=-105.4260 Z= 0.0000
X=-145.5461 Y=-105.4790 Z= 0.0000 (0+464)