ConTeXt: Define command for table

Question

Why is it not possible to define a command to create a table like this? I had no problem doing the same with a list

List Command:

\define[1]\docListBulleted
{\startitemize[before={\blank[small]},after={\blank[big]},inbetween={\blank[small]}] #1 \stopitemize}

MWE:

\define[1]\tabd
{\startxtable
    [option={stretch},split=yes]
    #1
\stopxtable}    
\starttext
\tabd{\NC  Elements \NC Amount  \NR}
\stoptext

The same (or similar) error occurs when I try to define the table with /definestartstop

MWE:

\definestartstop
[Asdf]
[before={\startxtable},
 after={\stopxtable}]    

\starttext

\startAsdf
  \startxrow
    \startxcell
      dddd
    \stopxcell 
  \stopxrow 
\stopAsdf

\stoptext

Answer 1

Extreme tables (aka xtables) are implemented using Lua buffers. These do not play well with macro definitions because the starting command has to “see“ the stopping command. From the manual:

Also apart from it not working, you should not use \definestartstop to wrap an xtable. Just use \definextable instead.

\define[1]\tabd{%
  \startembeddedxtable
    [option={stretch},split=yes]
    #1
  \stopembeddedxtable
}

\definextable
  [Asdf]
  [option=stretch,
   split=yes]

\starttext

\tabd{\NC  Elements \NC Amount  \NR}

\startxtable[Asdf]
  \startxrow
    \startxcell
      dddd
    \stopxcell 
  \stopxrow 
\stopxtable

\stoptext