I have been thinking for a while how i can reuse my code when building custom dataview webparts in sharepoint designer 2010.
So i decided to use the XslLink which is one of the properties when you edit a sharepoint webpart.
I started by creating a xsl file that i can use but after adding the link to the file like so:
<XslLink>sites/server/mycustomtemplate.xsl</XslLink>
I get the error : This web part does not have a valid XSLT stylesheet: There is no XSL property available for presenting the data.
So after some debugging i noticed it was the directory path for the link to the XSL style shee gets broken.
So i changed it to the full URL http://mysite/sites/server/mycustomtemplate.xsl it works
Enjoy