Display:

$<mmultiscripts>base(subscript\; superscript)*\; [\; <mprescripts/>\; (presubscript\; presuperscript)*\; ]\; </mmultiscripts>$

Source:

&lt;mmultiscripts>
<emph>base</emph> (
<emph>subscript superscript</emph>)* [ &lt;mprescripts/> (
<emph>presubscript presuperscript</emph>)* ] &lt;/mmultiscripts>