If the in an contains commas, the category is incorrectly split into multiple tags. For example, in today’s NY Times Front Page feed there is an item:
The second category is "Dunmore, Helen". In the trainer, this shows up as two tags: "Dunmore" and "Helen":
Fiction: A Novel of the French Revolution, Enacted in British Parlors
[...]
http://www.nytimes.com/namespaces/keywords/des">Books and Literature
http://www.nytimes.com/namespaces/keywords/nyt_per">Dunmore, Helen
http://www.nytimes.com/namespaces/keywords/nyt_ttl">Birdcage Walk (Book)

This seems like it is probably wrong.