During this step, Campaign associates the field(s) you specified when creating the audience level with the identifier field(s) of the same name in the user table. By doing this, you have specified that by default, when
Campaign makes selections from this user table, IDs are returned from the primary audience level.
For example, if you create an audience level named Account with the field
Acct_ID, and select this audience level as the primary audience when mapping the user table
Accounts, you have associated the
Acct_ID audience level field with the field in the user table that is the unique identifier (primary key) for the
Accounts database table.