It's not arranged by confirmation number. My confirmation #'s in order are:
Q3Fxxx
VV4xxx
KKJxxx
MNCxxx
I have always wondered that myself and it appears that whatever field is used to sort the data is not displayed on the My Itineraries screen. Date of purchase is also not the sort criteria because in my four itineraries listed above, they were purchased 4-2-3-1.