The current user’s operating system user ID.
A number, or $Null. Can be reset by an application program.
The current user’s operating system user ID; otherwise, $Null.
You can use the $UserID and $GroupID system variables to build levels of security into your applications.
During any Zim session, you can LOGIN under any defined UserName (in EntitySet Users). $ZUserID and $ZGroupID are then set to the UserID and GroupID associated with UserName; $UserID and $GroupID (containing values taken from the operating system) are still available for use.