key assignments

I recently purchased a Belkin Ergoboard one piece split keyboard to 
replace a keyboard that died.  I also have and continue to use on 
another computer a Kinesis Maxim two piece split keyboard.  I have 
also used two other two piece split keyboards, a PerfecTouch 101 and 
a LexMark.  The last three split the numbers between the 6 and the 
7.  The Belkin splits the numbers between the 5 and the 6.

Two typing books, Mavis and an old typewriter-based book, confirm 
that the standard key assignments are 6 and 7 to the index finger of 
the right hand.

A ruler confirms that the distance from the upper left corner of the 
right index finger's home key to the lower right corner of the 6 key 
is 1-1/4 inches (on a non-split full-size keyboard) while the 
corresponding reach from the upper right hand corner of the left 
index finger's home key to the lower left corner of the 6 key is 1 
inch.  At first glance the assignment of the 6 key to the right hand 
seems logical, except that it's a long way to reach, except when you 
split the keyboard!

Ben Cohen