<resources>
<string name="app_name">UnConv</string>
<string-array name="mainunit">
<item>Area</item>
<item>Pressure</item>
<item>Speed</item>
<item>Volume</item>
</string-array>
</resources>
i want to add some other values to the above items like a subgroup. Example for area i want yard, acre etc how can i achieve that?