Hi Stefan,
thanks for your kind reply.
I studied the XSLT script, located where to insert the filter statement you suggested and it worked, but it was just an example to make myself clear.
Infact the given expression (i.e. "[field]='some value') was just a reference and soon I realized I should have used a field comparison to a DNN Token value.
Here things get more complicated as XSLT scripts cannot access outer variables (DNN Token, URL, etc) and passing the needed DNN Token to the script from the UDT as a parameter (querystring) is not supported: I chose to change my way.
In Grid Table rendering, thanks to the embedded features of the form and List module, it's very easy to setup common use options like filters, sorting and so on, when you have to change to XSL rendering (generally to style the layout), I like say "good luck"...
Infact my goal was just to hide the column headers and I suppose it's easier to do that just using CSS, infact I'm looking at overriding the "Normal UDT_Table*" class for the header text color, in order to set it in the same color of the background. Much easier, isn't it?
Thanks for all.