This is how Predict generates the GFB.
I hope this will help you. See the fields AM1, AM2 etc.
Global Format G100006
FB=‘AA,8,P,AB,50,A,AC,15,A,AD,8,A,AE,10,A,AF’
‘,1,A,AG,10,A,AH,8,A,AI,8,A,AM1,5,P,AM2,5’
‘,P,AM3,5,P,AM4,5,P,AM5,5,P,AM6,5,P,AM7,5’
‘,P,AM8,5,P,AM9,5,P,AM10,5,P,AM11,5,P,AM1’
‘2,5,P,AM13,5,P,AM14,5,P,AM15,5,P,AM16,5,’
‘P,AM17,5,P,AM18,5,P,AM19,5,P,AM20,5,P,AM’
‘21,5,P,AN,2,U,AO,2,U,AP,8,A,AT,8,A,AQ,5,’
‘P,AR,5,P,AV,8,A,AX1,7,P,AX2,7,P,AX3,7,P,’
‘AX4,7,P,AX5,7,P,AX6,7,P,AX7,7,P,AX8,7,P,’
‘AX9,7,P,AX10,7,P,AX11,7,P,AX12,7,P,AX13,’
‘7,P,AX14,7,P,AX15,7,P,AX16,7,P,AX17,7,P,’
‘AX18,7,P,AX19,7,P,AX20,7,P,AX21,7,P,AX22’
‘,7,P,AX23,7,P,AX24,7,P,AX25,7,P,AX26,7,P’
‘,AX27,7,P,AX28,7,P,AX29,7,P,AX30,7,P,AX3’
‘1,7,P,AX32,7,P,AX33,7,P,AX34,7,P,AX35,7,’
‘P,AX36,7,P,AX37,7,P,AX38,7,P,AX39,7,P,AX’
‘40,7,P,AX41,7,P,AX42,7,P,AX43,7,P,AX44,7’
‘,P,AX45,7,P,AX46,7,P.’
Dieter Storr