(ii) two replicate, placebo-controlled, parallel group, 48-week trials [Trials 3 and 4] (iii) two replicate, placebo- and active-controlled, 6 week cross-over trials, with formoterol 12 microgram twice daily as active comparator [Trials 5 and 6] (iv) two replicate, placebo- and active-controlled, 6 week cross-over trials, with tiotropium HandiHaler 18 microgram once daily as active comparator [Trials 7 and 8].