User Identification is a property from the GAM Repository to set those attributes identifying a user.
The GAMRepositoryConfiguration Web Panel (located in GAM Example folder) is an example where this property is used.
The way to use it in GeneXus code (by using the GAM API) is the following:
&Repository.UserIdentification = GAMRepositoryUserIdentifications.NameEmail
Name and Email (default value)
Defines the GeneXus Access Manager (GAM) User Identification strategy. When using "Name and Email" means that both values must be unique, otherwise an error will occur. The "Name" value will check user Identification against the User Name only. While the "Email" value will check uniqueness on the User Email attribute.
GAM Repository features and properties