Answer to my own question was found in a PDF included with the Resource Kit from Nov 2011.
The Casper NetInstall Image Creator was developed to optimize the imaging process and
automate the creation of a NetBoot image.
Benefits
Using the Casper NetInstall Image Creator provides the following benefits:
- It does not create shadow files on the NetBoot server.
- Users do not have full access to the Finder unless permission is granted by the
administrator.
- The boot image is created automatically.
Requirements
The Casper NetInstall Image Creator is designed to convert OS packages created with
Composer or Disk Utility to NetInstall images without requiring manual configuration. It
is recommended that you begin the process with a fully bootable OS package and let the
Casper NetInstall Image Creator optimize the image automatically.