FWIW, I believe /etc/default/keyboard is populated by Ubiquity at some point during installation, so it's probably more reliable and user-specific than hard-coding 'us' in the XML file as well.
FWIW, I believe /etc/default/ keyboard is populated by Ubiquity at some point during installation, so it's probably more reliable and user-specific than hard-coding 'us' in the XML file as well.