[texhax] Can't use \d (dot below) with \edef

[Philip & Le Khanh]

Nasty.  This shews the cause --

	\edef \test {\halign {#1\crcr \crcr}}

but I can't remember whether this is documented.

Philip Taylor
--------
Wenlin Institute wrote:
> Dear TeX typesetters,
> 
> There is a problem with the Plain TeX macro \d for adding a dot below  
> a letter. Generally it works fine, but in a certain context it causes  
> an error, as illustrated by the following very short TeX program:
> 
> \edef\test{\d{u}}\bye
> 
> The error message is:
> 
> ------------------------------------------------------------
> ! Illegal parameter number in definition of \test.
> <to be read again>
>                     \crcr