Using User Defined Fields you can can assign a specific name to any Expression. The expression can then be accessed throughout the event file. They are defined in Main Window->Participants Data->User Defined Fields/Fcts.

For example, by default, the User Defined Field DisplayName is defined using this expression:

trim([Title] & "" & [Firstname] & "" & [Lastname])

DisplayName is being used on almost all lists to show that expression. If you do decide to use a different expression such as

UCase([Lastname]) & "" & [Firstname]

then you only have to change the User Defined Field once instead of modifying every single list.