Note that this byte is only read when items are used outside of battle; inside the item spell association table is used instead.
0x00 Sleep/Tent/Cottage effect
0x01 Max HP up by Power*10
0x02 Max MP up by Power
0x03 Strength up by [1..Power]
0x04 Stamina up by [1..Power]
0x05 Intellect up by [1..Power]
0x06 Agility up by [1..Power]
0x07 Luck up by [1..Power]
0x08 (Giant Tonic)
0x09 (Faerie Tonic)
0x0A (Strength Tonic)
0x0B (Protect Drink)
0x0C (Speed Drink)
0x0D Restore HP
0x0E Restore MP
0x0F Elixir/Megalixir (0 or 1)
0x10 Phoenix Down
0x11 Remedy
0x12 Use (Power)th Spell effect