Text structure, history, as reflected in the footnote nine, then it is impermissible, but otherwise, if there is a gap in the interpretations under the chevron doctrine, it is upheld. >> then when you talked about interpreting the statute, agency rule making. >> ordinarily it will be in agency rule making, or at least often. >> and there is an exception, correct? four major cases? what is the exception? for the rules of major economic or social significance, the supreme court has long made clear that the deference to the agency's will not apply in those cases. we expect congress, in the words ...