how to eliminate the last occurence of a character in xslt

I am using XML and XSL for printing the page in ASP.NET..

I am generating XML from Stored Procedure..

In that, I have the 'list of docs' columns.. Like Document 1, Document 2, Document 3,

In that I want to remove the appending comma character ',' (Only the last occurence)

If the String is Document 1, Document 2, Document 3,

I want the Output as Document 1, Document 2, Document 3

What method should I use??