A working QAM cable layout is a channels.conf file from your installation which is successfully tuning digital cable TV using an HDTV tuner card, along with the name of your cable provider, which tier you have (if applicable), and your zipcode (because many cable companies serve different channels from different headends) and user name.

If your services is not listed here, or in accurate, there are instructions for searching for QAM channels and finding unencrypted ones. If you're just trying to get an idea what's available in your area, you might find this website, operated by SiliconDust, the HDHomeRun tuner people, useful, for sufficiently small values of "useful".

Note: For those Comcast customers in an area where the Pace DC50X, Motorola or Thomson DTA's are being deployed, Comcast is broadcasting virtual channel maps that show QAM channel layouts. scte65scan is a utility that will read these maps.