We are transcribing a health/science book in UEB. References are made to chemical isotopes where superscript numbers are shown before the capital letter for the element. Is there a baseline indicator used in UEB? Examples shown in the UEB book on pages 172 and 173 do not show a baseline indicator for the subscript used in H2O.
No, there is not a baseline indicator in UEB. The superscript indicator only affects the next item. The definition of an item is found in Guidelines for Technical Material (GTM) 12.1. You can find examples of left-displaced superscripts and subscripts in GTM 7.8.