The Compose Character key[2][3] was introduced by engineers at Digital Equipment Corporation (DEC) on the LK201 keyboard, available since 1983 with the VT220 terminal.[4] The keyboard included an LED indicating that a Compose sequence is on-going.[5] While the LK201 introduced the group of command keys between the alphanumerical block and the numerical keypad, and the "inverted T" arrangement of arrow keys, which have become standard,[6] the compose key by contrast did not become a standard.