# Enums

- [FilterBinaryOperator](/legacy/legacy-experience/books/custom-books/api-reference/enums/filterbinaryoperator-enum.md)
- [FilterUnaryOperator](/legacy/legacy-experience/books/custom-books/api-reference/enums/filterunaryoperator-enum.md)
- [Filter Expressions](/legacy/legacy-experience/books/custom-books/api-reference/enums/filter-expressions.md): Learn about implementing filter expressions in your custom book project.