Fw: Metastock's formula into AFL

["Inwind" <pibotto@xxxx>]

Can someone please 
convert this Metastock's formula into AFL - Thanks
dn:= 1.0;up:= 1.0;gap:= 100*(OPEN - 
Ref(CLOSE, -1))/Ref(CLOSE, -1);prf:= If(gap>=up, OPEN-CLOSE, 
If(gap<=-dn, CLOSE-OPEN,0));Cum(prf);

Thanks 
Peter