Should we have a special tag for the "body" of a macro?

[Victor Porton <porton@narod.ru>]

I am developing a specification of macroses in XML.

<prog:macro name="f">
  <prog:arguments>
    <prog:argument name="x"/>
    <prog:argument name="y"/>
  </prog:arguments>
  <prog:value name="x"/> then <prog:value name="y"/>
</prog:macro>

or

<prog:macro name="f">
  <prog:arguments>
    <prog:argument name="x"/>
    <prog:argument name="y"/>
  </prog:arguments>
  <prog:body>
    <prog:value name="x"/> then <prog:value name="y"/>
  </prog:body>
</prog:macro>

?

prog:arguments should be optional (as in the case of zero arguments), I 
think.