Kind of chart or code (3)
I believe the answer is:
bar
I believe this is a double definition.
'kind of chart' is the first definition.
'code' is the second definition.
(bar code is a kind of code)
(Other definitions for bar that I've seen before include "shoal at mouth of river" , "Sandbank; pub counter" , "Drinks counter; restriction" , "Local" , "What drinkers head for" .)