Copyright notices are stored as supporting material elements. You can specify the default copyright for all elements in a particular plug-in by using the plug-in editor. See Changing the Default Copyright Notice for this procedure.
Sometimes elements in your plug-in may require a different copyright than the default for the plug-in. See Overriding the Default Copyright Notice for this procedure
Frequently a plug-in contains contributing elements with a different copyright than the base elements which receive the contribution. When there are multiple contributing elements, each with its own copyright notice, the individual copyrights are appended to each other in the generated page on the published site.
When you create a new plug-in you should also create a supporting materials guidance element with the appropriate copyright information. See Copyright Notices in a New Plug-in for this procedure.