The 'units in space' limit seems to count each GROUP of units as a single entity. This makes sense given that Groups of units are treated as a single ship in combat (All fighters fire together, damage is 'streamed' from one unit to the next, etc.) So, just read "number of unit Groups" for the real definition of the limit.
[This message has been edited by Baron Munchausen (edited 16 February 2001).]