A basic requirement for linked data is that records include structured and clear data about topics of interest or searched Things, formatted in ways that allow linking to other data. While linked data presents great potential for the library community, libraries' existing digital knowledge is largely inaccessible, stuck in the increasingly obsolete MARC format, readable only by humans and certain library systems. To maximize the value of linked data using library content, important entities and relationships must be defined and made available, codings that are machine understandable must be adapted for linked data purposes, and persistent identifiers must be substituted for text. The Virtual International Authority File aggregates identifiers published by numerous sources in a variety of domains and languages to help produce a linked data collection of information on given topics, making possible rich linked data that is machine readable and presented in the user's language. Since 1994 the Program for Cooperative Cataloging (PCC) has worked toward cost effective uniformity of library standards. The PCC's ultimate goal is to transition from MARC to linked data through widespread adoption of standards and best practices by the library community.