debian mentors/ commonpackagingmistakes/ copyright
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Copyright

All software works can be copyrighted. This involves putting Copyright (C) <year> <your name> at the top of any file that you create. You then become the copyright holder of that work.

It is important to know who the copyright holders of a package are as they have special rights over the package. To this end Debian says that all copyright information must be documented in the debian/copyright file.

This means that when you create a package then you need to go through each file of the package and find any person who asserts copyright on the file and add them to the list of copyight holders in debian/copyright. You should also note what files they assert copyright over in the file. Copyright includes both the name and the year(s), so you must include both.

If the source doesn't include copyright information then you should request that upstream add it.

This is related to Licenses, and you can do both tasks together.

It is a common mistake to see 

 Copyright:

Here are some useful links that explain a little more on the subject.