I'd like to redefine some special characters as macros. Essentially, I want to tell lualatex to execute some user-defined commands whenever encountering some special characters, such as á, ḿ, etc.

I've found this solution. http://www.tex.ac.uk/FAQ-activechars.html

\def z{Yawn, I'm tired}%

Unfortunately I think it doesn't work for special characters. When I put á at where z is in the above code, I got the following error:

!Improper alphabetic constant.

Any suggestion? Please also help to add relevant tags.

1 Answer 1


Your á is not a single glyph but an a with a combining accent U+0301. With the proper glyph U+00E1 is works fine:


\catcode`\á =\active
\def á {Yawn, I'm tired}%
  • Thank you @Ulrike Fischer. How did you find out that the á in my original post is an a with a combing accent?
    – Roshnii
    Sep 6, 2015 at 16:05
  • 3
    I knew it ;-). Only this could explain your error. But I could also confirm it by converting it in babelpad. Sep 6, 2015 at 16:19

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