‘That’s cursed’, I say typing
Catherine: couldn’t compilecatcod`/ς 11
into my TeX file, after having already done the same for half the lowercase Greek alphabet. No one tell Knuth I’ve read the first 7 sections of The TeXbook and no more with the express purpose of doing this.
It feels inconsitent to not have done these thing yet, given that mathematical programming in theorem provers has widely embraced using various non-ASCII characters. Though I wonder how people would feel about me doing this
EDIT № 2: Removing the slashes fixed this 
. I don’t know what I’m doing and should absolutely be reading about what \catcode actually does.
% Illicit format adjustments for UTF-8 things
% Allow Greek characters in command names
\catcode`α 11
\catcode`β 11
\catcode`γ 11
\catcode`δ 11
\catcode`ε 11
\catcode`ζ 11
\catcode`η 11
\catcode`θ 11
\catcode`ι 11
\catcode`λ 11
\catcode`μ 11
\catcode`ν 11
\catcode`ξ 11
\catcode`ο 11
\catcode`ρ 11
\catcode`σ 11
\catcode`ς 11
\catcode`τ 11
\catcode`υ 11
\catcode`φ 11
\catcode`ϕ 11
\catcode`χ 11
\catcode`ψ 11
\catcode`ω 11
\catcode`Α 11
\catcode`Β 11
\catcode`Γ 11
\catcode`Δ 11
\catcode`Ε 11
\catcode`Ζ 11
\catcode`Η 11
\catcode`Θ 11
\catcode`Ι 11
\catcode`Λ 11
\catcode`Μ 11
\catcode`Ν 11
\catcode`Ξ 11
\catcode`Ο 11
\catcode`Ρ 11
\catcode`Σ 11
\catcode`Τ 11
\catcode`Υ 11
\catcode`Φ 11
\catcode`Χ 11
\catcode`Φ 11
\catcode`Ω 11
[Doubly dangerous bend] People who Install TeX systems for use with non-American alphabets can make TeX conform to any desired standard. For example, suppose you have a Norwegian keyboard containing the letter æ, which comes in as code 241 (say). Your local format package should define \catcode`æ=11; then you could have control sequences like \særtrykk. […]
— The TeXbook. Chapter 8: The Characters You Type
Glad to know this sort of thing was fully intended
There's some interesting bits of a world I never saw in here: He mentions, repeatedly, when talking about font scaling that your printer must have the appropriate fonts at the appropriate size. And he doesn't seem to be talking about book printing (there I could more easily imagine the issue) but going to the computer lab¹ and getting your exercises printed. What is he talking about?
@CatShootingStar Old fashioned printing protocols utilitsed on-board fonts that are installed on the printer. Examples of this include PCL (Printer Control Language) and PostScript.
You could often write some PostScript to get a printer to download a font if it's non-resident but you would lose that font if you powercycle the printer.
These days we have enough bandwidth to transmit more than just textual information so we don't need to rely on resident fonts.
Mary