I have ran an experiment that uses an incomplete latin square design and I am not sure how to run it with SPSS. So I've got 3 tasks, called R, I and P, but participants only completed two of them (which gave me 6 possible combinations: IR, RI, IP, PI, RP, PR). They then repeated the tasks in the same order, so I have a repeated measure between time 1 and time 2.

How can I set up my data to analyse it correctly with SPSS?