One use of this field might be to specify mapping information between this OpenEdge domain and an operating system domain when the authentication system is _oslocal on a Windows system, which supports its own domains. In this way, a Windows user might extend the built-in validation of their Windows user name with some other ABL check involving their Windows domain as well.
A user-defined authentication system with a configured ABL authentication callback might accept a variety of options, depending on the user account system that the callback relies on to authenticate user credentials.
For more information on the syntax of the options you can specify in this field, see section on using ABL callbacks in authentication systems in OpenEdge Development: Programming Interfaces.
