Adding a variable to the workflow expression engine

[Guido1982]

Hm, that's weird. In my install, the assigned user for the invoice defaults to the one on the SO it was created from...

I tried:

Code:

<field>
    <fieldname>assigned_user_id</fieldname>
    <Orgfields>
      <Orgfield>
        <OrgfieldName>$(assigned_user_id : (Users) id)</OrgfieldName>
<OrgfieldID>FIELD</OrgfieldID>
      </Orgfield>
     </Orgfields>
  </field>

But that gave very weird results. Any way I can add the 'id' field to the expression?