create dynamic xml attribute names

Hi,

I'm trying to create a single xml template that can handle dynamic attribute names. The attribute name to be used is stored in another attribute. Please have a look at how i set up the xmltemplater to write the attributes names:

ROOT:

<root>

<a>head</a>

<feat>

{fme:process-features("SUB")}

</feat>

</root>

SUB:

<f>

<{fme:get-attribute("attr")}>{fme:get-attribute("value")}</{fme:get-attribute("attr")}>

</f>

Where 'attr' holds the attribute name and 'value' the value.

I get the following error:

The following error occurred near line 2, column 6 of the query:

invalid expression: syntax error, unexpected character "{"

An error occurred while parsing the 'SUB' sub-template

So clearly this is not the way to go. Is this possible in anyway or do I have to define specific SUBs (conditional) for every possible feature schema?

Thanks!