Your right DJBMaster, vectors are by nature a set of three vars.
But the manual is 'blurry' because some functions are apparently "overloaded" to be capable of accepting
a> integer-vectors (never seen one of these though...)
b> standard-vectors (which are just three vars in a row in memory)
c> float-vectors (Ive never seen one used, but look at "_vec()" in the manual)

For a better idea of how the different game structures are built,
try taking a look at the .../GStudio7/includes/aTypes.H file.
JUST DONT ACCIDENTLY CHANGE ANY OF IT! or its re-install GameStudio time....
This will give you a good look at the "guts" of many game object structures.

Have fun...