Application Packaging Developer's Guide

The class Field

The class field names the class to which an object belongs. Using classes is an optional package design feature, and is discussed in detail in Writing Class Action Scripts.

If you do not use classes, an object belongs to the none class, and when you execute the pkgmk command to build your package, it will insert the CLASSES=none parameter in the pkginfo file for you. Files with file type i should leave the class field blank.