Neptune uses a combination of debian and own software sources.
On an installed system you can find the software sources under [b]/etc/apt/sources.list.d[/b].
They are divided in seperate files.

Neptune ships with two software repositories. The main one contains all neptune related configuration and applications + kernel. The second one is called the KDE Repo and contains all KDE SC applications and tools such as kmail or kontact. The KDE Repo is disabled by default. We also use the Kanotix LibreOffice Repository for LibreOffice. This repository is also disabled by default
Content of neptune64.list:
# Neptune 64Bit Sourceslist
deb http://proindi.de/zevenos/neptune/repo/ sid main

# Neptune 64Bit KDE Sourceslist
# deb [arch=amd64] http://proindi.de/zevenos/neptune/kde-repo/ sid main

# Kanotix LO4 Sourceslist
# deb http://kanotix.com/files/fix/lo ./