JDeveloper, Java & XML :: Looping And Querying Data From XML Clob

Our company database is Oracle based and we use SQL Developer to pull out needed data.Using a snippet borrowed from a co-worker, I have put together a query that, among other things, pulls a list value out of an xml clob field and displays it in the query results. My query as it stands right now is below, followed by an example snippet of the xml clob that I am pulling from. The reason for the "query within a query" is because the base query could return multiple entries and I only want the one with the most recent date.

select * from
(Select Wtr_Service_Tag, Wtr_Tran_Origin, Wtr_Send_Date, Wtr_Receive_Date,
to_char(substr(wtr_req_xml,instr(substr(wtr_req_xml,1,8000),'SID')+8,12)) Asset_Tag
from ws_transactions
Where Wtr_Service_Tag In ('20458749610')
And Wtr_Req_Xml Like ('%CSM%')
Order By Wtr_Receive_Date Desc)
where rownum = 1;
[code]....

This query is only able to pull the first value in the list.How can I edit this query to pull all of the list items when there are more than 1 (preferably concatenated into one column in the query results)? I have another field, in a separate table, that I can pull from to get the number of list items.

This one may be more complex. As currently written, the query pulls a fixed number of characters from the xml clob and either returns not enough data, or too much because the values I need to pull could be of varying lengths. I have no way to query what those lengths might be.