High-level Data Link Control(A protocol for information transfer adopted by the ISO. HDLC is a bit-oriented, synchronous protocol that applies to the data-link (message-packaging) layer (layer 2 of the ISO/OSI reference model) for computer-to-microcomputer communications)
High-Performance Media Access Technology(A recording format that can store audio, video, and pictures on a CD or DVD. HighMat discs play on any Windows computer and on some DVD players)
