As I think about how I can invite interested persons to contribute English & Telugu sentences text & audio content to raviiyer.org‘s Spoken English app., I am realizing that some persons/organizations may be interested to contribute data only if they get attribution. So raviiyer.org using CC0 (see: “Using CC0 license for Data”: https://ravisiyer.wordpress.com/2011/12/10/using-cc0-license-for-data/) may turn them off.
Here’s how Wikipedia seems to be handling it. It uses CC-BY-SA (Attribution and Share Alike). Share-Alike forces re-users to share mods. using same licensing terms, in this case, CC-BY-SA. It also used/uses GNU Free Documentation License. More details are available here: http://en.wikipedia.org/wiki/Wikipedia:Copyrights.
Interestingly the page states that contributors retain copyright to materials contributed – text and media. So contributors can republish and relicense their own data in any way they want. However the license for the copy of the materials given to Wiki by a contributor cannot be altered or retracted.
The list of contributors to a wiki page can be accessed via the “View history” link/menu at the top of the page.
Wikipedia also has disclaimers about validity of its content.
For raviiyer.org the Share Alike aspect of the CC license is not so imporant. I would like it to be permissive in terms of sharing. So CC-BY (http://creativecommons.org/licenses/by/3.0/) may be appropriate which allows people to freely use & modify & license on their terms but they have to give attribution to the data contributors. The data should include the names of the data contributors in text and, if appropriate, other forms like database table. The page having the download link for the data could also have a contributors link listing contributors.
The application using the data should ideally have a command which will list the data contributors (and the source code contributors).
This kind of approach may be satisfactory and motivating for some, if not most, contributors of data/content to raviiyer.org.
Disclaimer of validity of content is an issue that has to be examined. Does CC-BY have adequate disclaimers? If not, what disclaimers should raviiyer.org use?