I looked at the 3270 Character Set Reference and I can't see anything like this. That is not an overscore, but 4 dots. Note that there were a lot of character sets (fonts) for the 3270 family for languages (and special apps like APL). In addition to all the hardware character sets, there were also loadable character sets, but I don't think that is the case here.
Jim Elliott | Senior IT Consultant
GlassHouse Systems Inc.
That's cool. There is an Arduino-based interface for the coax connection. Now all that's needed is an actual 3278-2.