Yeah, all I could find was this disclaimer.<p><pre><code>  While Facebook has redrawn and shares these assets for the benefit of the design community, Facebook does not own any of the underlying product or user interface designs. By accessing these assets, you agree to obtain all necessary permissions from the underlying rights holders and&#x2F;or adhere to any applicable brand use guidelines before using them. Facebook disclaims all express or implied warranties with respect to these assets, including non-infringement of intellectual property rights.
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And this text at the end of the copy.<p><pre><code>  Feel free to use these files in any private or public space. Please do not repackage and redistribute these as your own.
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Needs an actual copyleft license on there somewhere before I use it.