Gentoo Development Guide

Licenses

All ebuilds must specify a LICENSE (note the American English spelling) variable. The value of this variable must be the name of a file in the Portage tree's licenses/ directory.

If the application is multi-license (either of several licenses can be used) then use the following syntax:

LICENSE="|| ( foo bar )"

Adding New Licenses

If your package's license is not already in the tree, you must add the license before committing the package. When adding the license, use a plain text file (UTF-8 encoded) if at all possible. Some licenses are PDF files rather than plain text — this should only be done if we are legally required to do so. Finally you need to check if your license should be added to a license group as listed in $PORTDIR/profiles/license_groups. For more information see the GLEP 23

It is not normally necessary to mail the gentoo-dev list or licenses@gentoo.org before adding a new license. You should only do so if the license could be considered 'questionable' or if you are unsure as to the meaning of any part of it.