When I type the following code in a comment:

\Gamma(X,\mathcal O_X) @>>> \mathcal O_{X,x}\\ 
@AAA @AAA \\ \Gamma(Y,\mathcal O_Y) @>>> \mathcal O_{Y,f(x)}

to generate: $$\require{AMScd} \begin{CD}\Gamma(X,\mathcal O_X) @>>> \mathcal O_{X,x}\\ @AAA @AAA \\ \Gamma(Y,\mathcal O_Y) @>>> \mathcal O_{Y,f(x)} \end{CD}$$

I end up with a warning box stating: Only one additional @user can be notified; the post owner will always be notified. It seems that it confuses between @>>> in the text mode and @>>> in the math mode.

This really should be fixed.

  • $\begingroup$ You don't need to require AMScd. It has been enabled globally. The problem is with the comment procedure disallowing multiple @ symbols unless ` is in the comment. Try that. $\endgroup$
    – Asaf Karagila Mod
    Dec 26, 2013 at 23:32
  • 4
    $\begingroup$ $$\begin{CD}\Gamma(X,\mathcal O_X) @>>> \mathcal O_{X,x}\\ @AAA @AAA \\ \Gamma(Y,\mathcal O_Y) @>>> \mathcal O_{Y,f(x)} \end{CD}$$` $\endgroup$
    – Asaf Karagila Mod
    Dec 26, 2013 at 23:33
  • 1
    $\begingroup$ \begin{CD}\Gamma(X,\mathcal O_X) @>>> \mathcal O_{X,x}\\ @AAA @AAA \\ \Gamma(Y,\mathcal O_Y) @>>> \mathcal O_{Y,f(x)} \end{CD} ` It works fine:! Thanks Asaf! :) $\endgroup$
    – user93957
    Dec 27, 2013 at 11:39

1 Answer 1


I agree that this is a bug. However:

  1. the AMScd package has been enabled by default for a long time now. No need to require it explicitly.

  2. If you have a ` symbol in your comment, then multiple @ symbols are ignored. It works out just fine, as the comments to your question prove.

    It's not a fix, but it's a temporary workaround.

  • $\begingroup$ You should have escaped the backtick symbol in item 2. $\endgroup$ Dec 27, 2013 at 4:06
  • $\begingroup$ I tried. It didn't work very well: ``` $\endgroup$
    – Asaf Karagila Mod
    Dec 27, 2013 at 10:26

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