ref: 1d760c9b3ea8eb5d7d0484cb66527c6a9d4eb5ea dir: /sys/src/cmd/hg/templates/rss/header.tmpl/
<?xml version="1.0" encoding="{encoding}"?> <rss version="2.0"> <channel> <link>{urlbase}{url}</link> <language>en-us</language>