https://nsf-gov-resources.nsf.gov/2023-04/EndlessFrontier75th_w.pdf
Authors. National Science Foundation
Venue. 75th anniversary volume, PDF (foreword by France Córdova)
How the Institute flags it
established 1 time frontier 1 time
This source carries more than one flag across the corpus. That is not an inconsistency to resolve: the same work can be established evidence for one claim and frontier evidence for another, and the flag belongs to the use rather than to the source.