To loop through complex PRPC Property/Page Types in an HTML rule - you can use the 'forEach' Pega Tag.

See this post here for an example of doing this: Re: Generate pdf dynamically with specific values from Pega UI

For convenience here's an example of the 'forEach' tag in use from that post:

<pega:forEach name="D_ChemList.pxResults">  
    <tr>  
       <td><p:r n="$THIS.Name" m="literal"/></td>  
       <td><p:r n="$THIS.AtomicNumber" m="literal"/></td>  
       <td><p:r n="$THIS.Block" m="literal"/></td>  
       <td><p:r n="$THIS.Description" m="literal"/></td>  
       <td><p:r n="$THIS.Group" m="literal"/></td>  
       <td><p:r n="$THIS.Occurrence" m="literal"/></td>  
       <td><p:r n="$THIS.Period" m="literal"/></td>  
       <td><p:r n="$THIS.State_at_STP" m="literal"/></td>  
       <td><p:r n="$THIS.Symbol" m="literal"/></td>  
    </tr>  
</pega:forEach> 

If you need to iterate through two complex types: you can nest the tags.

See the help sections entitled: "Stream processing of JSP tags" and "JavaServer Pages tags" for more information on using Pega Tags.

http://<yourprpc:port>/prhelp/procomhelpmain.htm#jsp/alphaList.htm

Cheers

John