Sentence:  If, on the other hand, reference is made purely to the root, we would expect all frequentative <WSD>jussives</WSD> to appear with a front element, producing "mɨt′ət′ɨs" instead of "mɨt′ət′ɨs" (19d). 
Meaning of the word marked with <WSD> tags:  The jussive mood, a verb inflection used to indicate a command, permission or agreement with a request; an instance of a verb so inflected.