any harm in allowing only ctrl-Q to restart output?

[Doug Gwyn <gwyn>]

Whether interrupt should unstall output depends on whether one
views DC3/DC1 flow control as user-controlled or as hardware-
controlled.  It is more important to get the hardware working
right, to avoid hung terminals (e.g. VT100 with VT640 graphics,
Teletype 5620).  Most fancy terminals that perform DC3/DC1 flow
control also coordinate this with user scroll control via ^S/^Q
or a scroll/no-scroll key.

There are UNIX terminal drivers that will continue dumping a lot
of characters to a terminal that has tried to stall by sending a
DC3.  The worst offenders are probably those that insist on using
input silo level alarms.  Such terminal drivers are broken and
should be fixed.  (This is possible, since there are also UNIX
terminal drivers that do this right.)

If your users can't be taught that interrupt doesn't automatically
unstall their terminal, then you have other worse problems to
worry about!  Try taping "TYPE CTRL-Q" notes on their terminals.