The following are counted as unemployment or underemployment:
1) Not working (unknown, unemployed, pursuing graduate degree)
2) Law school funded employment
3) Firms with less than 50 attorneys
4) State and local clerkships
5) One half of business/industry jobs
6) "Academic" jobs
Not every job in these categories is necessarily undesirable. However, there are good reasons to believe that most of the jobs in these categories are undesirable, given how much jobs in these categories have exploded from pre-recession figures. "Business" jobs and "academic" jobs, as well as school-funded jobs have increased dramatically.
Note Bene: I think Yale's fellowships might be legit. They show a large number of fellows in C/O 2010 data as well. U Chicago, meanwhile, shows a dramatic increase from just a few in previous years, to a couple of dozen last year.

In zoomable PDF here: https://docs.google.com/open?id=0B11ijy ... jE5OWdYUU0
Source spreadsheet: https://docs.google.com/open?id=0B11ijy ... zU3U2tidEk