[xsl] Grouping siblings according to attribute sequence

[Christian Sestier <christiansestier@xxxxxxxxxxx>]

Hi all,
I am using Saxonica\SaxonHE9.3N
I have the following source xml
      <terms>        <term level="1" termid="10" >        
 <value>ONE</value>        </term>        <term level="2" termid="8" >        
 <value>TWO</value>        </term>        <term level="3" termid="6" >        
 <value>THREE</value>        </term><!-- end of sequence = level number
restart at 1 -->        <term level="1" termid="3" >          <value>ONE
BIS</value>        </term>        <term level="2" termid="1" >        
 <value>TWO BIS</value>        </term>        <term level="3" termid="58" >  
       <value>THREE BIS</value>        </term>        <term level="3"
termid="45" >          <value>THREE TER</value>        </term><!-- end of
sequence = level number restart at 1 -->        <term level="1" termid="5" >  
       <value>ONE FOURTH</value>        </term>      </terms>
Sequence always start with level = 1term are in sequence levels that are
always in increasing order, 1, 2, 3, etc.Last item in the sequence can be
duplicated (more that twice) there can be up to 5 levels max
I would like to get the following :
      <terms>        <sequence>          <value>THREE/TWO/ONE</value>      
 </sequence>        <sequence>          <value>THREE BIS/TWO BIS/ONE
BIS</value>        </sequence>        <sequence>          <value>THREE TER/TWO
BIS/ONE BIS</value>        </sequence>        <sequence>          <value>ONE
FOURTH</value>      </terms>

Thank you to help me get started.
Christian