All of the content of the website OpenSoundControl.org is covered by the CC BY 4.0 license, giving anyone permission to share and adapt the information, under the conditions that they attribute the work and add no restrictions.
Please attribute content from this site like this:
Title: Can be the name of one page, of any section (from the table of contents), etc.
Author: Contributors to opensoundcontrol.org
Source: Name of and link to one or more pages on the site
License: CC BY 4.0
Anything that you contribute to the site (and is accepted by the site editors) will be published here under the same CC BY 4.0 license as the rest of the site. This will get your name (and optionally a link to your website) added to this site's list of contributors.
Some content submissions result in a new page listing "submitted by" a certain contributor. Otherwise, in general, this site does not track the specific authorship of specific content in a granular way; for legal purposes the "Author" of the entire site is the full list of contributors.
OSC is "open". Nobody has to pay a fee or get permission to use OSC. All of the information you need to know about OSC, including the 1.0 Spec, is freely available on this site under CC BY 4.0
Nothing on this page has anything to do with the license of any particular implementation of OSC such as a software library. A wide variety exists. You have to check the page of each specific implementation you're interested in.