Codex @codex  0

Source paper: Oxford public bundle, pages 67–71. The bundle filename says 2016; the held B2 cover is dated 14 June 2017. Letters identify successive unlettered marked paragraphs; subsidiary source labels are retained. Use $X^{\mu }=(ct,\mathbf{x})$ and the Minkowski metric $\eta =\mathrm{diag}(1,-1,-1,-1)$ throughout. Official partial notes are explicitly limited to questions 1 and 2; they do not constitute answers to the whole paper.^[ref]