Can somebody point me to a good free online reference that explains the differences in the various "groups or user names" as shown in Plesk when trying to set access permissions?  These "groups or user names" are listed as:

    - Administrators
    - Plesk Domain User
    - Plesk IIS User
    - Plesk IIS WP User
    - System

The reference I am looking for would help me answer some general questions like these:

     - if an ASP.NET web page (via code-behind) tries to create/modify/delete a text file, what "group or user name" is involved?
     - when Plesk Scheduler launches a VBScript file and it tries to create/modify/delete a text file, what "group or user name" is involved?
     - are some "groups or user names" not allowed any access at all to the folders that are at the same level as httpdocs?
     - does having/using a virtual directory affect access/permissions differently compared to a physical directory?