EmEditor cannot generate Alt+NumPad codes, 01 thru 08. The one that it CAN generate: ALT+10 – then causes EmEditor to refuse to save your file as ASCII – claiming data will be lost.
Whereas, for example, NotePad2 will generate Alt+NumPad codes.
(They appear inverted with a rounded box around them):
ALT+01: SOH
ALT+02: STX
ALT+03: ETX
ALT+04: EOT
ALT+05: ENQ
ALT+06: ACK
ALT+07: BEL
ALT+08: BS
Interestingly, I can copy the codes from NotePad2 into EmEditor — which are then displayed as a graphic square and EmEditor will save the file without warning about data loss.