Manual:$wgRightsText

Details
If either  or  is specified then this variable gives the text for the link.

If using  then this value must be specified.

It's set at install time by the installer, either from its own predefined list or from the data returned from the Creative Commons license chooser.

If using  then the name of the page will also be used as the link if this variable is not set.

If you further want to remove the default copyright text, blank MediaWiki:Copyrightwarning if   is set, or MediaWiki:Copyrightwarning2 otherwise.

Example
This will render in the footer as:

The encapsulating text can be changed in MediaWiki:Copyright (message added on 2004-06-08).

This message is shown in the footer of the page and is not really supposed to contain valuable info which can't be retrieved elsewhere.

It's not easily retrievable via API, so it's a bad idea to put here important info especially if you declare to be using a license.

If you add additional links or formatting to $wgRightsText, this has to be done using wiki code, additionally you have to add the same content using HTML code to <tvar|msg>MediaWiki:Copyright</>.

Please be aware that the <tvar|noinclude> </> tags don't work and everything will be displayed / transcluded.

Licenses
Some available licenses are listed in this table: