Europe have different to USA which have different from Japan. Which is the one I believe is what Kokufu and all the Japanese clubs go by.
Again ambiguous. Mame = will fit in the palm of the hand. Shohin= under 20 cm, Chuhin= around 45 cm, Ippan= 45cm to around 1m.
In Europe the max size for Shohin is around 25cm which seems to be the excepted size in Australia, now.
In John Y Nakas techniques 1 page 121=122 he has a summary on sizes which I believe is what was used in the USA.
Large Bonsai ( omono bonsai ) the max was 1200 or 4ft not including pot. this is termed as as two to four man lifting tree.
Medium size ( chumono bonsai ) this size the average man can move around, and should be around 1 foot and a half ( 46cm ) to 3 feet tall ( 92cm )
One hand lifting size ( katade- mochi bonsai ) this size at about 8 inches to 15 inches ( 20- 38 cm) depending on the style rock clinging is not in this category.
Small size bonsai ( komono bonsai A tree of 4 or 5 inches to 7 inches ( 10cm= 18) will fall into this category this is a difficult size to get all the details.
Palm size bonsai ( mame bonsai ) this is the smallest bonsai and 3=4 should fit in the average size hand.
Then we have the microscopic size or poppy seed size (keshitsubu ) in this case it is a miniature pot and the seed is sown directly into the pot
In Deborah Koreshoffs book page 236 these are her guidlines Shito or keshitsubu up to 5 cm or 7.5 cm
Mame 5 cm 15 cm the above two classifications as shoohin or shohin . Kotate ( or Kotade ) mochi 15cm=30 cm.
Chiu or Ch-mono 30 cm= 60cm=. Dai or Omono 60 cm= 120cm or takes two to carry.
This I believe to be what is exceptable in Australia. I hope this helps in some way. Cheers

Pup