关于UPENN 30天答复的问题

我之前也看到咱论坛说可以30天不答复等其他学校，但后来看到GRAD CONNECT里面这句话：

Q: What is the deadline for returning the enrollment decision form?
A: For master's applicants, you must submit your decision form by June 1, although we would greatly appreciate a response within 30 days - our priority deadline - of when the decision is viewed

想问一下那个 priority deadline是什么意思？优先考虑的？

LZ要实在不放心就交吧。。免得一直担心