rexoverbey is right. I found this definition of HDMI.....
"HDMI (High-Definition Multimedia Interface) is the first industry-supported, uncompressed, all-digital audio/video interface. HDMI provides an interface between any audio/video source, such as a set-top box, DVD player, and A/V receiver and an audio and/or video monitor, such as a digital television (DTV).
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It transmits all ATSC HDTV standards and supports 8-channel digital audio, with bandwidth to spare to accommodate future enhancements and requirements."
On my A/V receiver, I'm using the FM antenna post for radio reception, and the speaker connections. Monitor out, s-video and analog out to a DVD recorder. And optical audio in between STB and receiver. The STB does not have HDMI capability, but the Pioneer Media receiver does, so the DVI to HDMI cable runs between the STB and the media receiver.
Since I added the HDMI cable after initial install, I left the existing component hookup in place, and I can switch between DVI/HDMI and component with the Pioneer remote.
My TV installer was a lot better at this than me. I'm lucky I know how to work everything.