Before revision: Patron-driven acquisition (PDA), also referred to as demand-driven acquisition (DDA), is a model of library collection development in which a library only purchases digital content, like e-books and e-journals, when it is clear that a patron wants them.
After revision: Patron-driven acquisition (PDA), also referred to as demand-driven acquisition (DDA), is a model of library collection development in which a library only purchases materials when it is clear that a patron wants them.