The rivet diameter should be at least three times the thickness of the thickest sheet being joined.
On the last page of NAS523.pdf, someone — Elias perhaps, or someone who had loved his idea enough to finish the sentence — had drawn a small mirror and written beneath it: "If you must build a ghost, teach it to answer questions of regret." nas523 pdf
The document itself is a technical datasheet or specification sheet. If you are looking for the NAS523 PDF specifically, here is what you need to know: The rivet diameter should be at least three
Based on historical summaries and cross-references, the standard covered: someone — Elias perhaps