ccREL is the Creative Commons Rights Expression Language. It is the standard recommended by Creative Commons for "machine-readable expressions of copyright licensing terms and related information". See http://wiki.creativecommons.org/images/d/d6/Ccrel-1.0.pdf for the entire white paper about ccREL.
Creative Commons have defined six pre-packaged licenses that seek to allow creators to retain copyright but to grant persmissions to make use of their work in specific ways. (There is also a CC0 license that grants all rights, placing the work in the Public Domain). These licenses all grant rights beyond "fair use" and are designed to maximize re-use of content. These pre-packaged licenses have been fairly widely implemented and tools have been developed to search various content repositories that support CC-licensed content. (See, for example, Creative Common's own search tool).
ccREL is Insufficient
c:Reproduction - copying the work in various forms.
cc:Distribution - redistributing the work.
cc:DerivativeWorks - preparing derivatives of the work
The one possible prohibition is
cc:CommercialUse - using the Work for commercial purposes.