If a package spans more than one volume, the class action script is executed once for each volume that contains at least one file belonging to a class. Consequently, each script must be able to be executed more than once. This means that executing a script any number of times with the same input must produce the same results as executing the script only once.
When a file is part of a class that has a class action script, the script must install the file. The pkgadd command does not install files for which a class action script exists, although it does verify the installation.
A class action script should never add, remove, or modify a path name or system attribute that does not appear in the list generated by the pkgadd command. For more information on this list, see item 1 in "How Classes Are Processed During Installation".
When your script sees the ENDOFCLASS argument, put post-processing actions (like clean up) into your script.
All administrator interaction is restricted to the request script. Do not try to obtain information from the administrator using a class action script.