4.3.4 Command $1A Details IC-746

$1A $00 Read/Write Extended Memory Command

$FE $FE $4A $E0 $1A $00 mn1 mn2 sel f15 f14 f13 f12 f11 mo1 fi1 fg1 STx11 STx12 STx13 SRx11 SRx12 SRx13 f25 f24 f23 f22 f21 mo2 fi2 fg2 STx21 STx22 STx23 SRx21 SRx22 SRx23 n1 n2 n3 n4 n5 n6 n7 n8 n9 $FD
Read/Write extended memory contents
The data layout is specific to the IC-746. The IC-7400 (IC-746Pro) uses a different memory layout. From the second set of data (Frequency, Mode, Filter, Flags, Subtones) probably only the frequency is used when in split mode. Since the 746 supports only one mode per memory, the second mode is ignored, as well as the second set of subtones.
OK if data is acceptable
NG if any data item is not in range.
mn1, mn2 Memory number in BCD. (2 bytes)
f15-1 Frequency 1, RX frequency when dup or split (5 bytes)
mo1 Mode for frequency 1 (1 byte)
fi1 Filter for frequency 1 (1 byte)
fg1 Flags for freq.1: $01=Tx Subtone on, $02=Rx Subtone on, $10 DUP-, $20 DUP+
STx1 TX-Subtone for frequency 1 (3 bytes)
SRx1 RX-Subtone for frequency 1 (3 bytes)
f25-1 Frequency 2, TX frequency when dup or split (5 bytes)
mo2 Mode for frequency 2 (1 byte)
fi2 Filter for frequency 2 (1 byte)
fg2 Flags for freq. 2: $01=Tx Subtone on, $02=Rx Subtone on, $10 DUP-, $20 DUP+
STx2 TX-Subtone for frequency 2 (3 bytes)
SRx2 RX-Subtone for frequency 2 (3 bytes)
n1-9 Memory name, ASCII (9 bytes)

Thanks to Richard (N1QVT) who helped with clarifying the 746 memory layout.