SMPTE 292 is a digital video transmission standard published by the Society of Motion Picture and Television Engineers (SMPTE) which expands upon SMPTE 259 and SMPTE 344 allowing for bit-rates of 1.485 Gbit/s, and 1.485/1.001 Gbit/s. These bit-rates are sufficient for and often used to transfer uncompressed high-definition video. This standard is usually referred to as HD-SDI; it is part of a family of standards that define a Serial Digital Interface based on a coaxial cable, intended to be used for transport of uncompressed digital video and audio in a television studio environment. The “M” designator was originally introduced to signify metric dimensions. It is no longer used in listings or filenames. Units of the International System of Units (SI) are the preferred units of measurement in all SMPTE Engineering Documents.