[NTG-context] embedding ConTeXt code in an xtable

I am now using xtable to have an XMLish document to store a table. How I can embed ConTeXt code like $\Delta{}N_{\text{test}}$ in the external XML file file with the table? In other words, having mathematical notiation in the table header? I tried various things such as: \expanded{\xmlflush{#1}}