I just flew on the 340-600, and the row numbers in the seat map on the Iberia web site are not only illegible, they are also wrong!

The seat map seemed to say that row 35 was an exit row. (I say seemed,
because the numbers are almost impossible to read.)

The real exit rows in economy on the Airbus 340-600 (346) are the following:

row 10, seats A, C, J, and L
row 22, seats A, C, J, and L
row 37, seats A, C, J, and L

People will congregate in front of rows 10 and 37, due to proximity to the galleys and lavatories, but they have much more leg room than row 22 which iis just an ordinary exit row (but still more leg room than normal rows).