I am facing difficulty to get required output in different structureB of
<corres>. Find the below three types of tagging structure.

Not getting exact output if apply <xsl:for-each> on below three type of
scenario.

Desired Output

<corresp><x>Correspondence to</x> Anne Marie Darling,
<institution><department>Department of Epidemiology</department>,
<institution-name>Boston University</institution-name></institution>,
<street>715 Albany Street</street>, <country>USA</country>;
<email>amdarlin@xxxxxx <mailto:amdarlin@xxxxxx></email></corresp>

<corresp><x>Correspondence to</x> Anne Marie Darling,
<institution><department>Department of Epidemiology</department>,
<postal-code>02118</postal-code>, <country>USA</country>;
<email>amdarlin@xxxxxx <mailto:amdarlin@xxxxxx></email></corresp>

<corresp>Joanne Lawrence, Association of British Neurologists, Ormond
House, 27 Boswell Street, London WC1N 3JZ, UK;
<email>joanne.lawrence@xxxxxxxxxx
<mailto:joanne.lawrence@xxxxxxxxxx></email></corresp>

Kindly suggest.

Please also tell us whether you can use XSLT 2 or 3 as it looks to me
you want to wrap some adjacent nodes or nodes starting with a certain
elements into an "institution" element, such task are usually easier
with XSLT 2/3 and for-each-group group-starting-with or group-adjacent,
even if the mixed content you have will make it harder than using a
simple for-each-group.