Ooo, so its like that. Got these when i stumble in Google for a keyword Minas, found few blog and some related description. In which it describe, what price settlement are based on for OPEC member. It is referred as references basket (ORB), and for Indonesia the price are based on Minas (Indonesia) crude.

So, in the term of meaning ORB is weighted average of crude price of each member production. The price itself fluctuate, like last Feb 28th Minas crude price are higher than ORB (Minas at US$98.85/barrel and ORB at US$94.99/barrel).

These are meant as intermezzo, just another info i would like to share here.