Money in circulation includes not only cash but ANY dinar denoted instruments , generally called M2 !! The CBI's M2 is 80T...AS of the 2016 annual report. Could be MORE today.
The CBI reserves INCLUDE the dollar value of the GOLD and all hard currency, 51.5B AS of 1/2018.
The exchange rate is computed as '' reserves / M2''.... $51.5 B / 80T dinar = .000643 ! YES, THEY cannot cover ALL the dinar in circulation AT the advertised rate. How can that BE???
The .000860 is only a TARGET RATE. In the real world that is not unusual. MOST central banks operate "under water " this way.