I do believe there's a code and I am interested in the number of 'PP' references (pied piper, passport, pinpoint, pontius pilate, etc.). However, I believe the code's in the borders rather than the main story. Do some counts of the bigrams in the borders. That yields some interesting results - you certainly get four of something when you take into consideration the numbers referenced/implied in the poems and pictures. Just haven't quite cracked the 'why' (I know what the 'why' is - also in the borders - but combining it with my other border findings is proving a bit beyond me right now).