My earlier entry/rant, It's not Open Data, so stop calling it that... about the non-Open Data nature of a number of Canadian cities' Open Data initiatives is supported by the just released Ten Principles for Opening Up Government Information from the Sunlight Foundation. Specifically:
"Non-discrimination" refers to who can access data and how they must do so. Barriers to use of data can include registration or membership requirements. Another barrier is the uses of "walled garden," which is when only some applications are allowed access to data. At its broadest, non-discriminatory access to data means that any person can access the data at any time without having to identify him/herself or provide any justification for doing so.
The imposition of "Terms of Service," attribution requirements, restrictions on dissemination and so on acts as barriers to public use of data. Maximal openness includes clearly labeling public information as a work of the government and available without restrictions on use as part of the public domain.
The capability of finding information over time is referred to as permanence. Information released by the government online should be sticky: It should be available online in archives in perpetuity. Often times, information is updated, changed or removed without any indication that an alteration has been made. Or, it is made available as a stream of data, but not archived anywhere. For best use by the public, information made available online should remain online, with appropriate version-tracking and archiving over time.