uri-templates and optional parameters

I'd really like to have a uri-template [1] to express the following  
hierarchical URLs:

   http://loc.gov/issn/1046-8188
   http://loc.gov/issn/1046-8188/1908-08-22
   http://loc.gov/issn/1046-8188/1908-08-22/1
   http://loc.gov/issn/1046-8188/1908-08-22/1/25

with something like:

   http://loc.gov/lccn/{issn}/{date}/{edition}/{page}

What would be the best way to do this? I noticed a similar discussion  
[2] about optional parameters before but was left with the impression  
that I would have to investigate using wadl or extending uri-template.

Would I be best suited pushing optional parameters into the query  
string?

   http://loc.gov/lccn/{issn}?date={date}&edition={edition}&page={page}

I guess more than anything I wanted to say "yeah I'd like that  
too" ... and to suggest that the spec at least mention the issue in  
the spec.

//Ed

[1] http://bitworking.org/news/URI_Templates
[2] http://lists.w3.org/Archives/Public/uri/2006Nov/0048