Quadrant Map Dimensions
 

The Quadrant Map has the following maximum coordinates:

X: 67
Y: 49

Higher values get reduced to these, placed on the edge of the map just the same.

The minimum coordinates appear to be:

X: 1
Y: 1

Even though there appears to be room to use 0 and still be "on the map", SE5 throws access violations when I try to generate maps with 0 system coordinates.