> However, one of my support staff is using an emulator but can 
> only offer
> VT100 on a very old laptop and as such there is no 'BREAK' key on the
> keyboard.
> Question: is it possible for the Break instruction be 
> recorded on another machine and sent ?
> is the Break instruction de-codable to its ESC + 
> xxxx value ?

'Break' (the kind you're talking about) is not a code; it is a
hardware-signaling technique that basically pulls the RS-232 signal line
high (the 'space' state) for longer than could possibly be valid for any
character--typically 1/8 to 1/4 second. Most emulators have a
menu/command option to send a 'break'.

FWIW, the 'Break' key on IBM-style keyboards doesn't generate a 'break'
signal; it generates the scan codes E1,14,77,E1,F0,14,F0,77. Application
programs interpret the received 'Break' keystroke into something
meaningful to them. Which raises another possibility: the reason the
'Break' key's scan code is so long is that, to maintain compatibility
with older keyboards, it first sends the scan codes for 'Left Ctrl' plus
'Num Lock', which was the standard 'break' function before the 'Break'
key came along. See what happens in your emulator when you hold down the
left Ctrl key and press/release Num Lock.