This is a property of type Keyword and the allowed values are:
- CC-BY-SA-4.0
- CC-BY-SA-3.0
- CC-BY-SA-2.0
- CC-BY-NC-SA-4.0
- CC-BY-NC-SA-3.0
- CC-BY-NC-SA-2.0
- CC0-1.0
- CERN-OHL-S
- MIT
- GPL
- LGPL
- GFDL
{ "type": "PROPERTY_CONSTRAINT_SCHEMA", "constraints": { "type_constraint": "_keyw", "allowed_values": [ "CC-BY-SA-4.0", "CC-BY-SA-3.0", "CC-BY-SA-2.0", "CC-BY-NC-SA-4.0", "CC-BY-NC-SA-3.0", "CC-BY-NC-SA-2.0", "CC0-1.0", "CERN-OHL-S", "MIT", "GPL", "LGPL", "GFDL" ] } }