I wonder that I've played for so long without wondering this - but what's the difference between a movement cost of '0' and a movement cost of '-1' in the parameter data? Is one to show impassable hexes and the other for impassable hexsides? Is that it? Both impassable though. Thanks.
User manual - version 4.0 games - pages 152-153
Movement Cost: by Unit Class
For each Unit Class, these values given the movement costs in points for each terrain type. The movement costs are divided into two groups: those for hex terrain and those for hex sides. When the movement cost for a particular hex terrain is given as 0, such as for Water, then it indicates that the unit cannot move into that terrain. The movement cost for a given hex side is the additional cost that hex side adds to the normal movement cost. When the movement cost for a particular hex side is given as –1, such as for Cliffs, then it indicates that the unit cannot move through that hex side