Add new field to knock out fixtures: P (Preliminary), Q (Quarter Final), S (Semi Final), F (Final)

Would it be possible to enter the following as a round number in cup matches, in addition to the normal numeric value :
P (Preliminary)
QF or Q (Quarter Final)
SF or S (Semi Final)
F (Final)

The round number needs to be retained as numeric as it sorts by the round in order to draw the results table, but it would be possible to add an additional field. Where would you want this to be displayed ? As another column in the fixture list ?