# [NTG-context] Math letters in commands

Hans Åberg haberg-1 at telia.com
Mon Sep 12 22:02:02 CEST 2016

> On 12 Sep 2016, at 21:45, Hans Hagen <pragma at wxs.nl> wrote:
>
> On 9/12/2016 8:25 PM, Hans Åberg wrote:

>> But then there seems to be a bug in the LuaTex \letcharcode command: There must be a character between “$” and the first occurring \activecatcode letter. Possibly this also causes a bug in \startformula, as discussed before. > > it's not a bug .. tex looks ahead for a second$ and in the process expands  the next token which happens to be a letter at that point so it gets injected as letter (it's the way tex works)

I’m not sure what you mean here: I must write $‘𝐝𝐢𝐦’ 𝑉$, because $‘𝐝𝐢𝐦’ 𝑉$ will not see the \catcode‘=\activecatcode. So LuaTeX must see an ordinary letter after \$ before it can see an \activecatcode character.

It does not happen with TeX using
\catcode\‘=\active
\def‘#1’{\csname #1\endcsname}