Last modified: 2014-08-15 20:31:20 UTC
Looking at the current version of <http://reportcard.wmflabs.org/>, there are two graph categories: "Core" and "Other". There doesn't appear to be any explanation of what "Core" or "Other" means in this context. Some kind of introductory text might be nice.
"Other" is called "Secondary" now but the issue remains.