I am not sure about OWE...but there is at least this CX/UA RTW that has a rule on this...it is in fact officially allowed ??
more on this CX/UA RTW:
http://www.flyertalk.com/forum/Forum85/HTML/000177.html
2. TRVL MAY TERMINATE AT ANY PT SERVED BY THE PARTICIPATING CARRIERS PROVIDED THAT THE ENTIRE ITIN DOES NOT REFLECT TRVL GREATEER THAN THE RTW. GREATER THAN RTW IS DEFINED AS COMPLETING TRVL AT A PT BEYOND THE PT AT WHICH TRVL COMMENCED.