[Discuss-gnuradio] Incomplete FAQ? What is an 'i' underrun?

[Jason Uher]

I have been getting a lot of 'iU' outputs when I run my scripts, and I
found in the FAQ (here: http://gnuradio.org/trac/wiki/UsrpFAQ/Gen)
that:

    "u" = USRP
    "a" = audio (sound card)
    "O" = overrun (PC not keeping up with received data from usrp or audio card)
    "U" = underrun (PC not providing data quickly enough)

    aUaU == audio underrun (not enough samples ready to send to sound card sink)
    uUuU == USRP underrun (not enough sample ready to send to USRP sink)
    uOuO == USRP overrun (USRP samples dropped because they weren't
read in time.


So what type of underrun does the 'i' represent?

Jason