Currently there are five (5) "Cost is per" options:

1. Named Registrant - When someone signs up for your event, s/he is required to provide each attendee's name.  The cost is calculated on a per-attendee basis.  This is the most commonly used option.
   
2. Named Registrant and per Registration - When someone signs up for your event, s/he is required to provide each attendee's name.  The cost is calculated on a per-attendee basis, and there is also an additional fee assessed per registration.
   
3. Unnamed Registrant - When someone signs up for your event, s/he is only required to provide the number of attendees.  The cost is calculated on a per-attendee basis.
   
4. Unnamed Registrant and per Registration - When someone signs up for your event, s/he is only required to provide the number of attendees.  The cost is calculated on a per-attendee basis, and there is also an additional fee assessed per registration.
   
5. Registration (Skip Individual Registrants) - The registrant is not required to provide any information about the attendees.  A flat fee is assessed on a per-registration basis.