By Alfred Poor, dealnews contributor Over the years, the standards for High Definition Multimedia Interface cable, also known as HDMI, have been improved and revised. But have your HDTV and your cables caught up to each other? And how do you know what you've got on your hands? For years, HDMI 1.3 was the standard, but version 1.4 was released in June 2009, followed shortly by version 1.4a in March of 2010. The overall goal of HDMI was not only to make it easy for consumers to connect their televisions to home theaters, Blu-ray players, and other devices, but also to make life easier in other ways. As a result, the connector was also designed to carry other signals so that you could eliminate extra wires. And that's where the confusion can set in, because you won't always be able to find out the exact capabilities of your HDMI cable. For example, the HDMI cable can also carry sound signals. Not all devices support this feature, however, which is why you will often find a pair of RCA connectors associated with some HDMI ports, which can be used to carry the stereo audio signal. Another feature that has been part of the HDMI promise from the start is its ability to transport commands from one device to another. For example, if you choose to watch a Blu-ray or DVD disc, you just press one button on your remote. This will turn on the disc player, adjust the appropriate input selection on your home theater or HDTV, and make any other changes so that the image will appear on your screen. The promise of this feature remains largely unfulfilled, however, though some manufacturers have implemented it among their own devices. This means that you'll get some of this benefit, but only if all your components are from the same manufacturer. There's even more promise in the capabilities of HDMI 1.4a. Here are just a few of the things it's supposed to be able to do: Ethernet Support: The same cable that carries the video and audio signals can now also carry an Ethernet local network connection. It supports up to 100BaseT for 100 100Mb/sec bandwidth. Even better, this connection can be shared between devices. In theory, at least, you can plug your HDTV into your home network, and then your Blu-ray player and home theater and any other connected device can connect to the Internet using the HDMI connection to the television set. Audio Return Channel: If you have a home theater surround sound system, it can make your system sound great. But what happens if you still get television signals over the air directly into your television? You have to run a separate cable out of your HDTV and into your home theater system so that the sound can be sent through your surround system. Otherwise, you'd be limited to listening with your television's speakers. HDMI 1.4a provides for an Audio Return Channel (ARC) as part of the new specification, which eliminates the need for this return cable. 3DTV Support: The newest HDMI specification also provides support for various forms of 3DTV signals. There are different ways that the two images of stereoscopic 3D content can be encoded, and this standard can transport many of them from the source to the television. 4K Resolution: If you think that 1080p is not enough, then you'll want support for "4K" high definition images. This is equivalent to four 1080p images at a time, and requires much more bandwidth than current HDTV connections. HDMI 1.4a is capable of handling the extra data. There are additional features available, including the ability to communicate the type of content being shown so that all the connected devices can be adjusted automatically for the correct resolution and other settings. HDMI 1.4a also supports additional color space settings. If you want to find all the details of the specification, you can find them at the HDMI Licensing website. Which One Do You Have? Some of these features may sound appealing to many of you, and you'll want to make sure that you get them in your next HDTV or other home entertainment device. Well, it may not be as easy as you think. As it turns out, all of these new features are optional in the new standard. Just because a given product is HDMI 1.4a compliant does not mean that it will have all these new features, or even any of them. It even says so on the HDMI Licensing site: "Version numbers such as HDMI 1.3 and HDMI 1.4a are primarily of interest to manufacturers, and not very relevant to the consumer. Instead, it is recommended that you focus on the specific features and capabilities of the product you're buying, and not worry about which HDMI version is supported." In fact, all licensed products using HDMI are required to be HDMI 1.4a compliant if manufactured since June 2010. But that doesn't mean that you'll find all these features. For example, the Audio Return Channel (ARC) is already found in many home theater sound systems (like this Denon model), but in relatively few HDTVs (although some specifically list HDMI 1.4 support, like this Samsung 50" TV). And as far as I know, there are no products with HDMI support for Ethernet available on the market yet. So at this point, you'll have to go by the features listed in the manufacturer's specifications to determine what parts of the HDMI 1.4a specification are supported in a given product. Most products don't even list an HDMI version number at all. Note: The choice of HDMI features supported by your components has implications for what HDMI cables you use. I'll explain what you need to know about that in a future column. Alfred Poor, known on the Web as the HDTV Professor, is an independent technology industry analyst and freelance writer based in Pennsylvania, specializing in PC-compatible microcomputer hardware and software products. He was a contributing editor to PC Magazine and Computer Shopper, and currently is a columnist at HDTV Magazine.