I have come across some oscillators with two or three signal lines like the two examples below:
CMO with 2 WMA:
Per1:=Input("Length of CMO",1,100,13); 
Per2:=Input("Length of fast WMA",1,100,3); 
Per3:=Input("Length of slow WMA",1,100,13); 
Per4:=60; 
Perc1:=.95; 
Perc2:=1.05; 
A1:=CMO(C,Per1); 
A2:=Mov(A1,Per2,W); 
A3:=Mov(A1,Per3,W); 
UB:=(HHV(Ref(A1,-1),Per4)*Perc1); 
LB:=(LLV(Ref(A1,-1),Per4)*Perc2); 
MB:=(UB+LB)*.5; 
UB;MB;LB; 
A1;A2;A3;
MACD Multiple Indicator:
A1:= Mov(C,11,E)-Mov(C,30,E); 
A2:= Mov(Mov(C,11,E)-Mov(C,30,E),12,E); 
A3:= Mov(Mov(C,11,E)-Mov(C,30,E),25,E); 
A4:= Mov(Mov(C,11,E)-Mov(C,30,E),50,E); 
0;A1;A2;A3;A4
I am not sure about the interpretation of such indices and their use in a trading system. Can anybody help? Thanks.