From the Spiegel article: "Electronic codebooks, such as the Advanced Encryption Standard, are both widely used and difficult to attack cryptanalytically. The NSA has only a handful of in-house techniques. The TUNDRA project investigated a potentially new technique -- the Tau statistic -- to determine its usefulness in codebook analysis."
And: http://blog.erratasec.com/2014/12/that-spiegel-nsa-story-is-...
Which isn't to say the NSA isn't legitimately participating in IETF and taking such notes ... but that codenames can be taken out of context. ;-)