The four variables are copper for the 1s place, silver for the 10s place, gold for the 100s place and platinum for the 1000s place. They are the players currency. The item value would be translated into those four currencies, which would then be displayed individually.
Like so...
item_value=37
37 = 37 copper
or
3 silver 7 copper
item_value=1424
1424 = 1424 copper
or
14 gold 2 silver 4 copper
or
1 platinum 4 gold 24 copper
or
1 platinum 4 gold 2 silver 4 copper
item_value=27893
27893 = 27893 copper
or
278 gold 9 silver 3 copper
or
27 platinum 8 gold 93 copper
or
27 platinum 8 gold 9 silver 3 copper