Hi,

On Mon, 2019-04-01 at 13:05 +0200, Bruno Le Floch wrote:
> Other option: use an xparse environment with "o" signature as you are
> doing, then end the code with
> 
>     \peek_charcode:NT & { ... } { ... }
> 
> to detect "&" and replace it by an active "&" (or rather by the
> definition you have for it.

I finally got around to test this. Simply adding
  \peek_charcode_remove:NT & { \sdaps_array_alignment: }
seems to work perfectly!

Thanks,
Benjamin