When I type the following code in a comment:

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


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.

• 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. – Asaf Karagila Dec 26 '13 at 23:32
• $$\begin{CD}\Gamma(X,\mathcal O_X) @>>> \mathcal O_{X,x}\\ @AAA @AAA \\ \Gamma(Y,\mathcal O_Y) @>>> \mathcal O_{Y,f(x)} \end{CD}$$ – Asaf Karagila Dec 26 '13 at 23:33
• \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! :) – user93957 Dec 27 '13 at 11:39

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.
• I tried. It didn't work very well: ` – Asaf Karagila Dec 27 '13 at 10:26