How to make fonts bigger in **plain tex** math mode?

[Douglas Johnson]

On Apr 28, 2023, at 06:55, Philip Taylor (Hellenic Institute) wrote:

>On 28/04/2023 11:34, Ulrike Fischer wrote:
>
>>You introduced U+A0 (no break spaces) after some of the 
>>fontnames, and now TeX is looking e.g. for cmr7U+A0 and is a bit 
>>unhappy.
>
>I didn't /introduce/ them, they came from the PDF version of the 
>TeXbook from which I copied the relevant parts of Plain.TeX.  But as I 
>say, it works here under XeTeX, so I don't really know what your 
>problem is or where it originates — maybe your e-mail client ?

I also detect U+A0 nonbreaking space characters in your source. 
(Such a character is also present after the period at the end of 
the first sentence in your reply to Ulrike, quoted above.)

Since these characters aren't present in the canonical plain.tex 
file, I think it's fair to say that you introduced them.

If I replace those characters with ordinary spaces, your source 
compiles without error for me using tex and luatex.

-- 
Douglas Johnson
Savannah, Georgia, USA
dmj at panix.com