16 Association of Research Libraries Research Library Issues 302 — 2021 In this framework, we claim that investing in PIDs and open PID infrastructure should be recognized and adopted as a core sustainability strategy that can insulate research stakeholders from an unpredictable landscape in which scholarly communication services come and go. Furthermore, openly available PIDs containing rich metadata give tool providers and builders a connected ecosystem to work from and offer the library community the flexibility and assurance that the information contained within these systems is not dependent on a single provider or platform. Endnotes organization behind such tools as Unpaywall and Unsub— announced that 1. Shortly after Microsoft’s announcement, OurResearch—the they were building a similar service: “We’re Building a Replacement for Microsoft Academic Graph,” OurResearch Blog, May 8, 2021, https://blog.ourresearch.org/were- building-a-replacement-for-microsoft-academic-graph/. For more on the shifting landscape of scholarly discovery services in the wake of the Microsoft announcement, see: Dalmeet Singh Chawla, “Microsoft Academic Graph Is Being Discontinued. What’s Next?,” Nature Index, June 15, 2021, https://www.natureindex.com/ news-blog/microsoft-academic-graph-discontinued-whats-next. 2. Geoffrey Bilder, Jennifer Lin, and Cameron Neylon, “The Principles of Open Scholarly Infrastructure,” 2020, https://doi.org/10.24343/ C34W2H. 3. John Chodacki et al., Implementing Effective Data Practices: Stakeholder Recommendations for Collaborative Research Support (Washington, DC: Association of Research Libraries, September 2020), https://doi.org/10.29242/report.effectivedatapractices2020. An additional related work also explores concrete steps libraries can take to accelerate the sharing of research data: Tobin L. Smith et al.,