The introduction of ISTA Procedure 3C, and more recently, 3A have brought about what could be a significant trend in the design and testing of packages intended for distribution through "Parcel Delivery Systems". Compared to the requirements of the historical and traditional Procedure 1A alternative, these new protocols represent significant, and perhaps unrecognized, challenges for the designers of packages for shipment in these important delivery systems. This presentation will discuss some of the issues, particularly those which Sealed Air has encountered in their efforts in these areas over the past few years.