Common cables used for digital stage boxes are Cat 5e, Cat 6, Cat 7, and fiber optic cable. The EtherCON locking connector is commonly used for twisted pair cables. Whilst these cables may be informally referred to as "ethernet", they do not necessarily use the Ethernet protocol, merely the same cables. Many manufacturers use proprietary standards for the transmission of digital audio, for example Behringer's ULTRANET, Digigram's EtherSound or Allen & Heath's dSNAKE. Open standards such as AES10 (used by DiGiCo, Soundcraft, Yamaha etc) and AES50 (used by Midas, Behringer, Klark Teknik) also exist.