This directory is used to enable cross-distro support and set baseline ISO packages needed for it to boot. A list of packages is needed for the *host* to build the ISO as well, which you'll find detailed below. Adding distro support is easy; there simply needs to be the following added:
"pkgs" should contain a list of the specific package names needed to install for that specific distro (as this isn't always standardized).
"meta" is a file consisting of the following variables (enclosed in single or double quotes, please:
NAME=<Distro - this should match the name of the directory this file is in!>
SUPPORTED=<yes or no- yes by default>
CHECK_METHOD=<a command that will be run that should return '0' (success) on *only* this specific distro
(or fully compatible derivatives, i.e. CentOS/RHEL)>
PKG_MGR=<a command used to prefix installation of packages e.g. for RHEL, "yum -y install">
PRE_RUN=<a command to be run before PKG_MGR (e.g. on Ubuntu, "apt-get update"). commonly used to update package caches/metadata.
if your distro does not require this, set PRE_RUN=none >
PKG_CHK=<a command that will be run that should return '0' (success) *only* if any given package in the pkgs file is installed. e.g. for RHEL, "rpm -q">
Oh- and your distro *must be able to install the package*. That means if you need to enable/add additional repositories, be sure to do so ahead of time.