[gradsusr] Subscript and superscript

[MY]

Hi, Sudev,

'draw string Nm`a-2`n'   ;* superscript

'draw string N`bm`n'      ;* subscript

Please test them.
Good luck!

MY

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YING, Ming
Shanghai Typhoon Institute of China Meteorological Administration
166 Puxi Road, Xuhui District, Shanghai, 200030
PR China
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