What is a `Part`?

[Werni2A]

The binary files contain

• [D] Parts
• [S] Parts Directory

however I haven't seen any content in the directory. What elements are required in the schematic such that they end up as a part?

I'm also not sure what the difference is between a part and a package. How does OrCAD define them?

Symbols are something like off-page-connectors or power symbols, while packages are schematic "symbols" for components like a resistor or some IC.