1. High-bit-rate digital subscriber line (HDSL) is a telecommunications protocol standardized in 1994.

2. It compares the technological economy ratio and practical applicability of HFC, HDSL, ADSL and FTTC.

3. Refers collectively to all types of digital subscriber lines, the two main categories being Adsl and SDSL.Two other types of xDSL technologies are High-data-rate DSL (HDSL) and Very high DSL (VDSL).