Board Thread:Questions and Answers/@comment-8959286-20130927152419/@comment-16571503-20140208100250

While it is possible for the ES on the belt to be E5 the style of the S is different from the 5 in No.5. It might not be that clear in the low res picture, but it is in the High res version in the game.

Also, the zeroth prime field might very well be either Es or N(nu) which would make all Prime Fields Es. Also Es isn't really the real formal name for the Embryo Storage, it's Jigen Kyoukai Seshokuyo Sotai (示現境界接触用素体, Manifistation Boundary Interface Prime Field Device). The exact same reading as the other prime fields, only the Kanji for Dimension is change to Manifistation.