Persistent IDs are popular! Here are some other types of persistent identifiers you might encounter:
Research Organization Registry (ROR): a collaboration between the California Digital Library, Crossref, and DataCite, ROR is an open database of persistent identifiers for research organizations
Open Funder Registry (OFR): maintained by Crossref, the OFR is an open database of grant-giving organization names and identifiers.
FAIR Facilities Project: a Research Coordination Network (RCN) project to explore the needs and possibilities around persistent identifiers for research facilities and scientific instruments.
Research Resource Identification (RRID) Initiative: hosted by SciCrunch, RRID is specific to biomedical fields. The initiative assigns identifiers and provides a search portal for organisms, antibodies, plasmids, cell lines, software, and databases.
For even more detail and additional PIDs, check out the National Transportation Library’s Guide to persistent identifiers.