I asked the organizers if they would allow submissions using Pd and received the following reply:
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Thanks for your mail and your interest in the competition.
We have discussed your question and - since max/MSP and PD are so similar - we have decided to allow works made in PD as well.
I hope that this applies to you so that we might hear from you again when the deadline of the competition approaches :0)
Best wishes,
Marie Büchert, Coordinator SPOR 2007
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Cheers,
Eric