On Wed, Jan 23, 2008 at 05:52:04PM +0200, Nicu Buculei wrote:
- in the upload form, you use checkboxes for license, it should be radio
buttons, for example why would I choose both PD and another license?
No, checkboxes are correct. You wouldn't want both PD and another license, but dual-licensing in the general case is quite common. For example, images uploaded to Wikimedia Commons have to be GNU FDL (or public domain, or fair-use), but if you prefer CC, or if you consider FDL too restrictive and want to license under MIT or BSD, then you can choose dual-licensing, allowing users to pick which license to use.
A more pertinent example: suppose you're designing the logo for a software project, like Firefox. You want to release under a CC license, but you know that CC licenses do not count as DFSG-free, so to match the rest of the project you can dual-license with CC and GPL (or whatever license the rest of the project uses).
Licenses are not mutually exclusive: they are additive. When you're working in isolation, dual-licensing is completely unnecessary, but if you're interacting with different groups of people, allowing them to choose a license gives them more freedom to use and reuse your work, which is (I suppose) your aim in using a free license in the first place,