Based on current information, "n4p2.zip" typically refers to a used by various governmental environmental agencies—most notably the Pennsylvania Department of Environmental Protection (DEP)—for storm water and permit reviews.
Documentation for Pennsylvania Natural Diversity Inventory clearances. Download n4p2 zip
When you download and extract the n4p2.zip file, you generally find a collection of forms and checklists required for a "completeness review". Common files include: The main application for permit coverage. Based on current information, "n4p2