Christine Lemmer-Webber@sivy @jessmahler {"http://www.w3.org/1999/xhtml/vocab#license": "https://creativecommons.org/publicdomain/zero/1.0/"} will do it. You can always add shorthands in your @context if you want to keep it shorter than that.
Jonkman Microblog is a social network, courtesy of SOBAC Microcomputer Services. It runs on GNU social, version 1.2.0-beta5, available under the GNU Affero General Public License.
All Jonkman Microblog content and data are available under the Creative Commons Attribution 3.0 license.