The mobile daughter card, also known as an MDC or CDC (communications daughter card), is a notebook version of the AMR slot on the motherboard of a desktop computer. It is designed to interface with special ethernet (EDC), modem (MDC) or bluetooth (BDC) cards.
Intel MDC specification 1.0
In 1999 Intel published a specification for mobile audio/modem daughter cards. The document defines a standard connector (AMP* 3-179397-0), mechanical elements including several form factors, and electrical interface. The 30-pin connector carries power, several audio channels and AC-Link serial data. Up to two AC'97 codecs are supported on such a card.
Several form factors are specified:
References
Mobile daughter card Wikipedia(Text) CC BY-SA