unicode-math
The author of fontspec developed a companion package called “unicode-math”. In 2009 it was in its infancy and supported very few fonts – and did not support Times New Roman, which was used for the formulae in the Bitcoin White Paper {Rosendahl1 [134] {G/7/46}}.
Further, the early versions of unicode-math suffered from a load-order problem: when used together with the “amssymb” package that defines additional mathematical symbols, the unicode-math package needed to be loaded before the amssymb package. Dr Wright’s White Paper LaTeX Files load unicode-math after amssymb, meaning that TeX would have issued an error for every one of the 2307 mathematical symbols defined by the former package {Rosendahl1 [136] {G/7/46}}.
Mr Rosendahl acknowledged in his report that these features could in theory have been resolved by working on the source code privately. That was seized upon in his cross-examination in which it was suggested that “it would have been technically possible in 2008/2009 for Dr Wright to have customised the code to … enable the use of Times New Roman” {Day17/30:22-24}. In re-examination, Mr Rosendahl confirmed that this would have taken “a matter of weeks, for someone with the technical knowledge” {Day17/35:15-16}.
However:
Dr Wright has not produced a single document evidencing any private work on the source code for the unicode-math package;
Dr Wright lacked the capability to develop any such source code. The Developers reminded me of his evidence that “I know LaTeX. I don't -- I'm not an academic, I don't teach it, so I don't know all the terminology.” {Day15/132:13-14}. There is also no reference to LaTeX in his contemporaneous CVs – an odd omission if he was developing related code at the time.
The unicode-math package was in the event only used by Dr Wright with Times New Roman in his so-called White Paper LaTeX Files for one thing: the Greek letter . {Rosendahl1 [137] {G/7/46}}. The Bitcoin White Paper uses the Times New Roman font in all its formulae, but Dr Wright’s White Paper LaTeX Files wrongly do not: see Rosendahl1 [153-154] {G/7/49}. I agree that it beggars belief that Satoshi Nakamoto would have spent weeks working to revise the unicode-math package for the benefit of using a non-standard font on a single character.