preferred_name: nitrate(in) + nitrite(out) <=> nitrate(out) + nitrite(in)
preferred_name_lc: nitrate(in) + nitrite(out) <=> nitrate(out) + nitrite(in)
label: nitrate(in) + nitrite(out) <=> nitrate(out) + nitrite(in)
label_lc: nitrate(in) + nitrite(out) <=> nitrate(out) + nitrite(in)