A binary package built with xbps is a normal tar(1) archive, compressed
with gzip, bzip2 or lzma and has the following structure:

	/
	/usr ------|
	/var ------| => Package structure that will be installed.
	/etc ------|
	...
	/var/cache/xbps/metadata/$pkgname
	/var/cache/xbps/metadata/$pkgname/flist
	/var/cache/xbps/metadata/$pkgname/props.plist
	/var/cache/xbps/metadata/$pkgname/postpre-action.sh

Metadata info is stored in the "/var/cache/xbps/metadata/$pkgname"
directory and two files will be always be present: flist and props.plist.

The flist file contains the list of files that the package will
install. The props.plist file is a proplib(3) property list and
has the following structure:

<dict>
	<key>architecture</key>
	<string>x86_64</string>
	<key>installed_size</key>
	<integer>500000</integer>
	<key>configuration_files</key>
	<array>
		<string>/etc/foo.conf</string>
		...
	</array>
	<key>run_depends</key>
	<array>
		<string>bofh-2.0</string>
		<string>foof-1.1</string>
		...
	</array>
</dict>

This plist might be extended in the future if it's required or useful.

Additional scripts might be added to trigger some actions at pre/post
installation stages.