<form>
  <lexicon lang="en" params="getLexiconParams()">
    <entry>
      <base>This text contains a {$var}.</base>
      <trans>A {$var} this text contains.</trans>
	</entry>
    <entry>
      <base>var</base>
      <trans>lexicon variable</trans>
    </entry>
    <entry>
      <base>This text contains a {$params_var}.</base>
      <trans>A {${params_var}} this text contains.</trans>
    </entry>
  </lexicon>
</form>