I have a requirement to transform a sequential XML node list into a hierarchical, but I run into some XSLT specific knowledge gap. The input XML contains articles, colors and sizes. In the sample below 'Record1' is an article, 'Record2' represents a color and 'Record3' are the sizes. The number of colors and sizes (record2 and record3) elements can vary.

<root>
 <Record1>...</Record1>
 <Record2>...</Record2>
 <Record3>...</Record3>
 <Record3>...</Record3>
 <Record2>...</Record2>
 <Record3>...</Record3>
 <Record3>...</Record3>
 <Record3>...</Record3>
 <Record3>...</Record3>
 <Record1>...</Record1>
 <Record2>...</Record2>
 <Record3>...</Record3>
 <Record3>...</Record3>
 <Record2>...</Record2>
 <Record3>...</Record3>
 <Record3>...</Record3>
 <Record3>...</Record3>
 <Record3>...</Record3>
</root> 

All fields are on the same hierarchical level, but still I have to create this structure as output:

<root>
 <article>              -> Record1
  <color>               -> Record2
   <size>...</size>     -> Record3
   <size>...</size>     -> Record3
  </color>
  <color>               -> Record2
   <size>...</size>     -> Record3
   <size>...</size>     -> Record3
   <size>...</size>     -> Record3
   <size>...</size>     -> Record3
  </color>
 </article>
 <article>              -> Record1
  <color>               -> Record2
   <size>...</size>     -> Record3
   <size>...</size>     -> Record3
  </color>
  <color>               -> Record2
   <size>...</size>     -> Record3
   <size>...</size>     -> Record3
   <size>...</size>     -> Record3
   <size>...</size>     -> Record3
  </color>
 </article>
</root>

I've tried to iterate the nodes sequentially but for example the 'article' (=record1) node tag needs to remain unclosed while 'color' (=record2) nodes are processed. The same counts for processing 'size' (=record3) having 'color' unclosed, but that is not allowed by XSLT. My next idea was to call a template for every article, color and size level, but I don't know how to select for example all 'record3' nodes between the current 'record2' and the next article represented by 'record1'.

I've also got a limitation on the XSLT version because I need this transformation in BizTalk Server which only supports XSLT 1.0

Can someone push me in the right direction?