A call name is the name someone was commonly known by — more formal than a nickname, but not necessarily their first given name. The call name is used in narrative reports after the person has been introduced by their full name.
The call name is also useful for keeping compound names together. For example, "Mary Ann Smith" would normally be shortened to "Mary" after the first mention in a chapter. Setting the call name to "Mary Ann" ensures she is always referred to as "Mary Ann". The same applies to names that should not be split, such as "St John" or "St Clair".
Enter the call name on the Naming tab of the Current Person Other Detail dialog.