In general, openness scores are based on the format and licensing of the datasets, the comprehensiveness of metadata, and what download options exist.
Dimension 2.2: Online access - Terms of Use Score
This openness element measures whether data are made available under an open license. Open licenses must allow the use, reuse, and sharing or adaption of data for commercial and noncommercial use without any obligation other than attribution, per the Open Definition. Licenses prohibiting commercial use or having two or more additional stipulations are classified as “Not Open”. Licenses with no more than one additional stipulation are classified as “Some Restrictions.” Licenses that do not explicitly state all allowed uses under the Open Definition and do not include restrictive language are also classified as “Some Restrictions.”
Our source for this indicator is Open Data Watch.  Scores range from 0-100.  For more details, consult the ODIN technical documentation.
This openness element measures whether data are made available under an open license. Open licenses must allow the use, reuse, and sharing or adaption of data for commercial and noncommercial use without any obligation other than attribution, per the Open Definition. Licenses prohibiting commercial use or having two or more additional stipulations are classified as “Not Open”. Licenses with no more than one additional stipulation are classified as “Some Restrictions.” Licenses that do not explicitly state all allowed uses under the Open Definition and do not include restrictive language are also classified as “Some Restrictions.”