OK+ means the panelist discovers solid problems and articulates them well. This appears to depend on the quality of the code basis. Because all code bases are somewhat flawed, however, the quality of the presented code doesn’t really affect your ability to get this grade.

OK means the panelist asks pertinent questions and discovers some problems.

OK- means the panelist asks questions and some of them are pertinent.

ZERO means the panelist didn’t ask any questions or asked too few questions pertinent to the code/design at hand.