I would look at the BA files with a huge grain of salt because historically they have been notoriously inaccurate. I would personally put far more creedance in the starfiles than the BA files, especially since the starfile and the info on the oneworld website are identical while the info from BA is different. The starfile *does* reference the 20 segment limit but does not reference a four segment limit. I expect that whoever wrote the BA file mixed up the Circle Trip with the Oneworld Explorer but maybe it is something new. Maybe markdu would be kind enough to just check if there has been any modifications to the starfile. Should be easy enough to check by comparing the date at the end of the file. If there has not been changes then I suggest just booking through a carrier other than BA.