Professor Sir Tim Berners-Lee's Open Linked Data Standards
|★||Make your stuff available on the web (whatever format)|
|★★||Make it available as structured data (e.g. Excel instead of image scan of a table)|
Editor's note: Excel is now more or less an open format, so this is not a great example!
|★★★||Non-proprietary format (e.g. CSV instead of Excel)|
|★★★★||Use URIs to identify things, so that people can point at your stuff.|
|★★★★★||Link your data to other people’s data to provide context.|
We at data.soton publish 5 star data and most of our individual datasets are 5 stars. Some datasets are voluntarily rated 4 stars because it's not sensible to link it to anything external (eg University jargon), but all our datasets link to at least one other dataset.