Sample patron types and categories: 

Type:           Categories:

Adult patron - default patron type
                PT  - Patron
                ST  - Student
                BH  - Homebound

Child - patron with a guarantor
                K   - Kid
                J   - Juvenile
                YA  - Young Adult

Organization - patron is an institution, not a person
                ILL - Inter-library Loan
                SC  - School
                L   - Library

Professional - a member of an organization (organization is guarantor)
                T   - Teacher
                S   - Staff
                B   - Board

Types are currently hardcoded, but you can add/edit/delete categories after installation from the administration module.
