Restrict lines on layout

Hello Gurus,

I'm using BW 3.5 and BPS.

I create a BPS layout based on a two characteristics on line.

Users want to see first all the characteristic values and, after, to restrict on one or two values.

I tried to put a variable on this characteristic but this is not the good solution. With a variable, users could see the characteristic only value by value.

so anybodyknows how to filter the list after launching the layout with all the values?

Thank's

David