Translations:PKGBUILD/18/en

The license file(s) should be included in: /usr/share/licenses/pkgname/, e.g. /usr/share/licenses/foobar/LICENSE.
If the source tarball does NOT contain the license details and the license is only displayed elsewhere, e.g. a website, then you need to copy the license to a file and include it.
Add custom to the license array. Optionally, you can replace custom with custom:name of license. Once a license is used in two or more packages in an official repository (including [community]), it becomes a part of the licenses package.

The BSD, MIT, zlib/png and Python licenses are special cases and could not be included in the licenses package. For the sake of the license array, it is treated as a common license (license=('BSD'), license=('MIT'), license=('ZLIB') and license=('Python')) but technically each one is a custom license because each one has its own copyright line. Any packages licensed under these four should have its own unique license stored in /usr/share/licenses/pkgname. Some packages may not be covered by a single license. In these cases, multiple entries may be made in the license array, e.g. license=('GPL' 'custom:name of license').
Additionally, the (L)GPL has many versions and permutations of those versions. For (L)GPL software, the convention is:
- (L)GPL - (L)GPLv2 or any later version
- (L)GPL2 - (L)GPL2 only
- (L)GPL3 - (L)GPL3 or any later version
If after researching the issue no license can be determined, PKGBUILD.proto suggests using unknown. However, upstream should be contacted about the conditions under which the software is (and is not) available.