There is a futures formula that I don't quite understand. I hope someone who knows can help me explain, especially what the lines of SUMBARS and BACKSET mean.

DIFF:(EMA (closing, 12)-EMA (closing, 26));

DEA:EMA(DIFF，9)；

MACD:(2*(DIFF-DEA))，COLORSTICK

SC:=CROSS(DEA，DIFF)；

SC 1:=SUMBARS(SC， 1)； {The number of days since I last wore DIFF in DEA}

JC:=CROSS(DIFF，DEA)；

JC 1:=SUMBARS(JC， 1)； {Days since I last wore DEA on DIFF}

JC2:=SUMBARS(JC，2)； {DIFF2 times, the number of days from the previous time to the present in DEA}

a 1 1:=(MACD = LLV(MACD，sc 1))；

a 12:= BACKSET(a 1 1，sc 1)； {Backset (A 1 1, SC 1) Here is a future function, and the lowest point of MACD in the near future is set to 1}.

A 13:(REF(A 12, 1) and (a12 = 0));

A 14:SUMBARS(A 13， 1)；