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From the very early specifications and draft standards, the CableCARD module has been a two-way device. That is, it included the functionality to enable two-way communication on the cable plant. This two-way communication is necessary for a variety of advanced cable services including video on demand (VOD), switched digital video (SDV), interactive services and applications.
The media has frequently reported that first-generation CableCARD 1.0 modules are one-way devices. This is simply not true.
CableLabs had always intended to develop the CableCARD module and host receiver standards with two-way capability. However the manufacturers of digital TVs requested that a host standard be developed that only had one-way capability. This one-way cable-ready receiver was defined by the FCC's Plug & Play order and by the Joint Test Suite (JTS). It is the definition of this one-way receiver that lacks the ability for two-way functionality, not the CableCARD module. While the FCC defined the elements of the one-way cable-ready receiver, CableLabs continued to define specifications for two-way receivers.
When a CableCARD 1.0 module is used with a two-way receiver (e.g., Samsung HLR5067C) that card supports all the necessary two-way functionality for VOD, SDV, and other interactive services.. . .http://www.opencable.com/primer/cablecard_primer.html
This article is very good and there is a lot more information that I didn't include.
Click the link below for an article from the FCC requesting comments about two-way features on cable systems (Note: It is in a PDF format):http://hraunfoss.fcc.gov/edocs_publi...C-07-120A1.pdf