DOCSIS = Data Over Cable Service Interface Specification
Developed by CableLabs and approved by the ITU in March 1998, DOCSIS defines interface standards for cable modems and supporting equipment
DOCSIS specifies downstream traffic tranfer rates between 27 and 36 Mbps over a radio frequency (RF) path in the 50 MHz to 750+ MHz range, and upstream traffic tranfer rates between 320 Kbps and 10 Mbps over a RF path between 5 and 42 MHz. But, because data over cable travels on a shared loop, individuals will see tranfer rates drop as more users gain access.
For More Information, check out
CableLabs
DOCSIS is to cable modems, what V.90 is to 56K dialup... it's just an operating standard.
DOCSIS is only in the US... overseas they use a similar standard called Euro-DOCSIS