How to superscript the ambiguous citation?

I am having some troubles editing the output style.

I want to superscript a letter after the year to make citations from the same author published in the same year distinguishable from each other. 

There’s no superscript option, so i could’t make it supercript.

what should i do? 

Thanks

The superscripting citation style is generally applied to “numbered” output styles, not “lettered” ones. Since there’s already a current lettering convention to distinguish works by the same author (which is standard, accepted practice and provided by the Endnote output style) superscripting the letters is unconventional and incorrect style-wise - which may explain why Endnote does not have a built-in user controlled feature to permit the formatting. However, if you wish to pursue this track you can superscript the letters in MS Word by manually selecting then italicizing the letter(s)*.

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*Note:  To prevent the formatting from  reverting back to the original  non-superscripted style  (which may occur  when updating  the citations) you can either: 1)  make the formatting changes on a copy of the  document, which was converted  to text  (to  remove the Endnote  field codes.); or 2) make the formatting changes  the last  task  when finalizing the  document  and turn off instant formatting  before doing so.