Table 1.

The list of action codes used in the notation system of action grammar.

codea	action	categories used in Inoue-Nakamura & Matsuzawa [29]	description
T	touch	touch, kiss	touch object with hand/foot/mouth
CH	change horizontal angle	roll	change the angle of anvil with horizontal rotation
CV	change vertical angle	roll	change the angle of anvil with vertical rotation
CP	change position	pull, push	change the positioning of anvil by horizontal movement on the ground
G	grasp	hold, lift, pick, grasp, take, peel	grasp and lift up object with hand
H	hit	hit	hit object with/without holding another object in hand (numerals were deleted if repetitive hits were observed with the same set of objects)
P	pile	put	put object on another object and release the hand
V	reverse	turn	turn over object and reverse it upside-down
W	wipe	brush	wipe surface of object and brush away broken shells
S	support	support	support object to fix it by keeping contact with hand/foot
D	drop/disassemble	drop	drop object from hand or disassemble object from a set of combined objects
B	bite	mouth, bite	bite object in hand with mouth
E	eat	eat	eat kernel of opened nut
R	replace	replace	replace nut on stone for better positioning
U	put	put	put object on another object and retrieve it without releasing the hand
F	floor		release object in hand onto the floor
L	fall		object fell off from a set of combined objects
M	miscellaneous	step, lay, press, kick, hug, sit, fling, point, rake, scrounge

^aA capital letter indicates that the action was performed by the right hand and a lower case letter that the action was performed by the left hand.